I had typed out a long paragraph about why I'm less stressed, but I realized the tl;dr is - I figured out what matters to me, and, more importantly, what doesn't. When you figure out what's NOT important, it's like a big weight being off your shoulders.
That and probably decreasing testosterone levels ;)
When I was younger, I was always stressed about how I would pay the bills. When layoffs would go around I would be super stressed , worrying about what if it happens to me. I'd also be stuck dealing with some asshole boss because I needed the money again causing more stress.
Right now there is a rumor going around that my company is not doing too well financially. In the past I would have been worried about it. Now my only thought is if I do get laid off, is where I do some traveling to. If it is during the summer, think I'll go spend some time in the Canadian Rockies. If during the winter, I'll go back to Australia.
Long-term disability insurance and life insurance are nice to have too. Patio11 has been preaching this [1] but it took me a while to really get it. The technical detail of "own occupation" is really important here.
When I was laid off last year I did have the option to continue the disability insurance, but it was a bit more expensive that what I was paying as an employee. IIRC it went from $50/month to $100/month.
What is nice is that my new employer picks up the tab 100%, but it is only 60%. Usually in the past I would pay a bit extra to get 75%, but that is not an option.
I've never thought about private disability insurance before, but it is something that I should look into.