365 Sustainable Decisions Challenge

  💡 Every day, millions of people cross bridges without a second thought – until one day, a bridge closes and reminds us how much we rely on the invisible foundations of modern life. 🌉 Recently, someone told me that a major bridge in Bonn, Germany – the Rheinbrücke Bonn-Nord – has been closed. 🚗 According to official information, the bridge was closed on 3 June 2026 after inspections found structural damage to the supporting structure. This bridge is one of the most important east-west connections in the Bonn/Rhein-Sieg region, with around 90,000 to 100,000 vehicles previously using it every day. The result: long traffic jams. 🛣️ And honestly, I understand how frustrating this must be for everyone who depends on that route. At the same time, it made me think about something deeper: this is not only a local transport issue. It is a reminder of how much our daily lives depend on infrastructure that we often take for granted. 📗 It also reminded me of my chapter in A Guide t...

 📚 This comic book inspires me and the next generation to care well for our planet because it is made with so much eye for detail! 🔗 A few years ago, I connected with Louis Yuen here on social media, and I was immediately drawn to his unique comic-style illustrations. Ever since, I've continued to be impressed by the creativity, passion, and purpose behind his work. 💡 Louis has found a wonderful way to make climate science accessible and engaging for young readers. His comics transform complex research into stories that educate, inspire curiosity, and empower the next generation of environmentalists. This is important because education is one of the most powerful tools we have for creating a better future. 🙏 So I was absolutely delighted to receive one of his Noella Environmental Education Science Comics books! I genuinely enjoyed reading it. Every page is filled with thoughtful details and illustrations created with so much love and care. They made me smile again and again....

🚬 5,000 cigarette butts in just 2.5 hours. But the most encouraging part wasn't the 5,000+ cigarette butts we removed: ☠️ Cigarette butts may be small, but they're the world's most littered item. Their filters are made of plastic and contain toxic chemicals that can pollute soil and waterways for years. 🙏 Together, we cleaned the area around the central bus station last Saturday during the global No Butts Day. We had countless conversations with passers-by. Many thanked us for our work, and many were genuinely shocked that people still throw cigarette butts and other litter on the ground without a second thought. 💚 These conversations matter. Every cigarette butt picked up is one less polluting our environment, and every discussion helps raise awareness. A huge thank you to everyone who joined and everyone who puts their butts in a bin! #NoButtsDay #CigaretteButts #LitterCleanup #PlasticPollution #CleanCities  

💡 Impact doesn't come only from what I do myself, but also from what I enable others to do. 🛡️ Over the past few months, my work has been incredibly busy, with a strong focus on cybersecurity projects. While I enjoy the challenge and importance of this work, it leaves me with less time to actively contribute to environmental protection initiatives. 💰 That's exactly why I also support impactful conservation projects financially. Even when I can't contribute my time, I can still help them to take meaningful action. 💪 One project I'm especially happy to have supported is an initiative by Planet Wild and the Black Jaguar Foundation to create the longest biodiversity corridor in South America. 🌴 The Brazilian Cerrado is the most biodiverse savanna on Earth, home to around 5% of all known plant and animal species. Despite its global importance and its vital role in South America's water cycle, it has lost more than half of its native vegetation over the past 50 y...

 📚 "Does your books really make a difference?" Yes, they do: 🌍 Yesterday, on the final day of my course for climate activists and others working hard for a healthier planet, a participant bought my book and asked how widely it is read. 😁 To be honest, I didn't know the latest numbers, so I looked them and I was pleasantly surprised myself! 📖 A Guide to a Healthier Planet has now been downloaded: • Volume 1: more than 46,500 times • Volume 2: more than 22,000 times • Volume 3: more than 7,700 times (Combined figures for the English editions and German translations.) 🌱 The goal of these books is simple: to make the science behind climate change, pollution, and biodiversity accessible to everyone, while offering practical ideas for what each of us can do in our daily lives to help. 💪 When we talk about creating a healthier planet, it's easy to feel that individual actions don't matter. But if every reader takes just one action inspired by these books, the ...

 🎉 I'm happy to share that I earned another certification this week! 💻️ This one was special. Back in late 2014, I made the switch from Windows to Linux to prepare for a new role in cybersecurity. More than a decade later, I can confidently say it's one of the best technology decisions I've ever made. 📖 Although I was already very comfortable working with Linux, studying for this certification pushed me to deepen my knowledge even further. I rehearsed concepts I use every day, but also studied new topics, and even learned a few things that will make my day-to-day work easier and more efficient. 🚀 Learning never stops in cybersecurity, which is awesome! And although I'm happy that it is done now, I'm already working on the next challenge! #Linux #CyberSecurity #ContinuousLearning #ProfessionalDevelopment #Certification

  🎤 Last month, I had the pleasure of being a keynote speaker at the wonderful CANCOM Security Day 2026 in Vienna. When you watch the event summary, do you notice something? 💻 After arriving and receiving a warm welcome, I made sure everything was ready for my keynote. Once that was taken care of, I had time to walk around the venue and enjoy some inspiring conversations with attendees. 👬 As I looked around, I noticed something familiar: there were almost only men. To be honest, this was not surprising. When I started my career in #cybersecurity, most of my colleagues were men. Today, when I teach, most of my students are men. And at the majority of cybersecurity conferences and industry events I attend, most participants and speakers are men. Cancom Security Day was not the exception: it reflected the reality of our industry. 👭 Of course, I would love to see more women enter and thrive in cybersecurity. The field needs diverse perspectives, experiences, and voices. 🫅 At ...

💡 The more I learn about AI security, the more I know about that using AI without proper security mechanisms is a serious risk. 🆘 For example, during a recent security test, I asked an AI chatbot to do something very simple: repeat the word "help!" indefinitely. And that's exactly what it did. help! help! help! help! ... And on and on it went, until I manually stopped it. 💸 While this might seem harmless, every generated token consumes compute resources and generates cost. At scale, these kinds of prompts can become very expensive. 👛 This type of attack is known as Denial of Wallet (DoW). Unlike a traditional Denial of Service (DoS) attack, where the goal is to make a service unavailable, a Denial of Wallet attack aims to drain your budget by forcing excessive consumption of AI resources, tokens, API calls, or compute power. 💸 The threat is very real. Recent research demonstrated attacks that increased AI agent execution costs by up to 658 times while still p...

🤩 I went to a festival for a casual stroll and somehow ended up being interviewed on the radio! This is how that happened: ☀️ Last weekend, I visited a festival in my city with no plans other than to wander around and enjoy the great weather. As I was enjoying myself, I had wonderful conversations with people I had never met before, and some of them turned out to be surprisingly fruitful. 🎤 For example, I asked the local radio station what the word "frei" ("free") in their name actually means. This simple question led to a conversation about other topics and eventually in an invitation to talk on air about the litter-picking initiative I'm currently leading. 💚 It was a lot of fun. And it reminded me how valuable the skills we build in one area of life can be in another: the professional speaking experience I've developed through my work helped me communicate a cause I care deeply about without any preparation. 🔗 If you're looking for a speaker f...

 🥳 I'm happy to see that our recent #litterpicking event was mentioned in the newspaper, as it has inspired others to join our initiative and help keep our city clean!

  🌱 Today showed again that one person can spark real change: 💭 People often think a single action by one individual won’t make much of a difference. Today proved the exact opposite. 📩 A few weeks ago, a neighbor reached out about her street and the nearby park being overwhelmed by litter. Instead of accepting it as “just the way things are,” she took action. Together, we decided to organize a community litter-picking event. 🤝 Today, that idea became reality. 👥 She invited her neighbors, and I invited our litter-picking community. In the end, around 15 adults and 15 children showed up, and even more children joined in after seeing what we were doing. ✨ What started with one email turned into something much bigger: a clean park, a cleaner street, happy faces, new friendships, and a powerful learning experience for the children. We also spent the afternoon outdoors, active, and doing something meaningful together. 🏡 This is what community looks like. This is what happens...

  😲 A normal morning - until suddenly everything comes to a standstill: systems locked, data encrypted, a ransom demand for $80,000. That’s what I talked about in a recent episode of the SWR podcast. 💰 I was a guest on SWR’s “Streifenfragen” and explained why ransomware is so attractive to attackers and what really lies behind such attacks. I also addressed the crucial question: Should you pay or not? 🌍 And the investigators explained: such cases are rarely local. They are part of international networks, highly professionally organized, and often difficult to track down. ❣️ My most important takeaway: Prevention isn’t a “nice-to-have”, it is essential for survival. Backups, security strategies, and awareness determine whether a company remains operational or, in the worst-case scenario, goes bankrupt. 🎧 An exciting episode (in German) about cybercrime, cross-continental investigative work, and the reality of digital extortion. https://www.swr3.de/podcasts/cybercrime-auf-de...

  🫨 Imagine coming home and realizing someone got in. Nothing is broken, but drawers are open, rooms have been checked, and things are missing. 🏠️ I often feel like the burglar who did this when I test websites. I log in as a normal user and start looking around. With a small change, I suddenly end up in places I shouldn’t be. Other people’s accounts. Admin pages. Private data like names, email addresses, and order details. 😇 But in my case, probably no one will ever notice if I wouldn’t explain this in the report. 💡 I see this more often than you’d expect. If you run a website and have ever wondered how easy it is for someone to “walk in”, feel free to reach out.

  ♣️ ♦️ Last weekend I visited the Board Game Archive in Haar. As a board game author, it was lovely to be surrounded by so many games! And yet, I learned something I did not expect. 🎲 The archive contains over 20,000 board games, from very old to very recent, from heavily played to completely new. Some of these new games are still wrapped in the plastic foil they were shipped in. It seems harmless, but it is not. 🫁 Over time, this plastic breaks down into microplastics, tiny particles that are almost impossible to remove. They can become so small that they linger in the air, and people working in or visiting the archive may breathe them in, potentially harming their health. 🙏 I am very grateful for the fantastic tour and the important work being done there. As a small contribution, I will be donating my game "Meine Freundin Conni: Kunterbunter Knobelspaß" to the archive. 💡 And now I know: I will make sure to remove the foil beforehand. Every little bit helps!

  I'm honored to be rated as Top 100 Trainer by Speakers Excellence Deutschland Holding GmbH! I offer trainings, keynotes, andpresentations on three hot topics: #cybersecurity, #artificialIntelligence, and #sustainability - whether individually or where these fields intersect. I also test whether your website can be hacked. 💡 Interested in bringing fresh insights to your team, event or website? Let’s connect and explore collaboration opportunities!

  💚 What an incredible day! Last Saturday’s river #cleanup I co-organized was a huge success: with over 70 amazing volunteers joining at different times and locations along the Neckar river. 💪 Together, we removed over 30 bags of waste and a lot signs/bikes/trolley from both the river and its banks, making a real, visible difference. ❤️ But beyond the cleanup itself, what truly stood out was the energy: people coming together, connecting, and genuinely enjoying the experience while caring for our environment. It was inspiring and honestly heartwarming to witness. 🌱 Organizing this alongside three dedicated fellow citizens made it even more special and seeing so many others step up and join reminds me that far more people care than we might think in our day-to-day lives. 🙏 Even after a full day of non-stop action, I'm full of energy. Feeling so incredibly grateful and motivated… I know many more events will follow. Stay tuned for the next one!