Panicking and paranoia is counter productive.
If you do "lot of risky and dangerous shit" then it's even more important that you do so mindfully. If you get careless because you are tired you increase the risk.
Personally my "trick" is to learn from others, e.g. in few weeks in Paris there will be https://splintercon.net/paris/ where tools and processes will be explained. I can learn from them.
Also my way to stay calm isn't just to be mindful or learn... but do stuff, no matter how small. If you learn about a new thread, address it today. It doesn't mean fix the problem entirely (it'd nice if you could) but rather do something, ANYTHING, about it. If it's not solved, write notes about it and resume tomorrow or whenever you can. Every small effort does add up over time.
Finally I find that sport helps a lot to "evacuate" stress. If I feel some pressure from work or the overall situation, I go outside and sweat it out. It doesn't magically make the World better but it insures I'm a bit more in shape to try to tackle whatever is thrown at me.