I am definitely a high stress individual. I would be a lot better off in terms of sleep, general health, and overall happiness if I were a lower-stress individual.
For years I have struggled with the concept that pretty much all the truly low-stress (not just average, but really chill) people I know just don't care. By and large I don't meet people who have some magical way of remaining relaxed despite bearing critical responsibilities that deeply affect others or despite being in pretty worrisome circumstances. Maybe those people are out there, but I don't see a ton of them. I meet chill people who have no motivation, have few big responsibilities, and whose lives are basically cushy. Obviously attempting to become a low-stress person by following these models wasn't going to work for me. I mean, I'd love a cushy life but it's unlikely to fall in my lap without some motivation, and I am unwilling to give up on caring pretty deeply about how what I do affects others.
But I am seeing a glimmer of another possibility. I still won't be extremely chill while still giving a shit, but there may be a middle ground. There are a few categories of stress: 1) responsibilities to others, and my worries that I am not doing well enough or could do better; 2) the cruel world that hates women, crushes chronic pain patients, brutally murders queers and nonbinary folk, and on and on. I can decrease both of these stresses somewhat. The first kind I can attack in multiple ways: know my limits (and forgive myself for them), work with colleagues to do better than I can do alone, communicate clearly and early and often, and get out of positions where my limits and their effects on those I serve are things I cannot accept. I can even decrease the second kind a little by asking for help.
I'm surprised it took me this long to notice these ideas. They won't be a cure-all. But I'm sure they can help.