When I was a kid, I don't think I was ever really stressed. I had a great life. Whether or not I was going to win that evening's street hockey game was probably my biggest concern.
As a teenager, more pressing concerns (or at least they felt pressing at the time) came into my life. I would usually turn to sports as my outlet. My practices and games were a place where I could be myself and release negative energy in a positive way. I don't mean that I would necessarily lash out at my opponents -- I was a mostly clean and sportsmanlike player -- but I did play contact sports, and I was able to be aggressive without it being a problem in my non-sports life.
When I first started writing, I did it because I liked it. I had some stories to tell, and it was a fun process to challenge myself and get the words on the page. I never really thought about the calming effect it was having on my daily stress levels until I realized that I couldn't not write. It no longer only makes me happy, it is an integral part of my life. Sending words through my brain and fingers onto the computer creates a giant release. After writing, I feel so calm. It's as if all of the characters in my head hashed out any issues I might've been having for me.
Obviously, some things in life are more stressful and worrisome than others, and big things will still be there once I stop typing. But, because of the frame of mind writing puts me in, they always seem so much smaller.
Some people do yoga. I write (type).