Haven't dealt with a lot of stress, but I probably will soon since I'm going to have to start homeschool stuff.
Depends on the situation, though. With the school stuff I mentioned, like my sister, I'm going to have to try reassuring myself I'm okay where I am and the worst that can happen isn't bad. (It'd only be a test, I mean, right?) Plus, there's really no due date for everything in the program I'm gonna use for my homeschool, so yeah. ^^ Although, obviously there are times I /should/ worry, but if it gets too stressful, I mean, I have a technique.
If I'm going somewhere like the doctor for example, again, I'll just reassure myself I'm okay and nothing bad will happen. That's usually my solution, probably, and if it's an emotional thing stressing me I think I'd seek a distraction and try to talk about it.
Sorry if I rambled about it, but yeah!