Here's a simple idea to ask yourself each time you feel stressed - "Is whatever I'm feeling stressed about going to really matter in 5 years time?".
You be surprised how rarely you get a "yes" if you are truly honest with yourself.
Another simple method is to take a 15 minute timeout and go for a walk or do something else that consumes your attention.
After those 15 or so minutes come back to whatever it is that is stressing you and break it down into smaller manageable chunks for you to deal with, one step at a time.
And also read Springboard's comment a second time to get the deeper meaning of his point.