I've done a lot of mental work over the last few years. I sought help for this in a lot of places - yoga, books, friends, professional advisement. One of the things that has helped me tackle big and small stresses is re-framing. I'm not a psychologist, thus asterisk on everything I say about this. Here's what helps me though:
Something (bad) happens. I see that something. I have feelings about it. I storyline it in my head. At the end of the story, I add "...and that's great."
Extremely large asterisk: this doesn't work for everything. There are life-changing incidents that surely will have no immediate silver lining.
Thankfully, most things aren't in that category.
Situation: I didn't get a promotion. A colleague got it. I deserved it. I'm jealous, angry, slighted, frustrated and sad. AND THAT'S GREAT.
Period. Another door has opened. There is a chance for reflection, growth, humility and courage.
I got second place. I failed at work. I missed an opportunity. I hurt someone. I wasted time. I wasted money. AND THAT'S GREAT.
To me, a psychology amateur, that is re-framing. Turning negative to positive. Subtracting minority of highly rare and devastating events, the majority of life's "failures" and "disappointments" are super super great. It takes practice and serious mental energy. It starts to get easier, routine unexpecteds and "small stuff" doesn't make an impact as much. Big things are handled easier with some focus. Even large life events can be contextualized better.
Would love any comments from all those folks smarter than I!