Powerlifting - It allows me to eat what I want whenever I want because my body burns more calories at rest. It also is a good outlet for stress and rewarding when you hit goals that you worked towards.

Calligraphy - Cheap to get in. Bought a parallel pen for something like $11 and some Claire Fontaine paper and started learning. It's very much a hobby that you get out what you put in. No artistic ability required, and it's very impressive to others. Rewarding when you see how pretty the letters you've created are.

Programming - I'm paid to write code, but I also do it for fun. I try to be creative with my projects and work on something random but still useful and challenging.