One of the biggest things that helps me save money every month is the fact that I genuinely enjoy doing things that are free. If I had a whole bunch of expensive hobbies, my monthly spending would be SO MUCH HIGHER just to entertain myself!
Think about the things that YOU do for fun. Do you like going out shopping? Do you like hanging out at restaurants? Do you go to the movie theater every week? Do you enjoy getting manicures and pedicures?
Individually, each of those activities isn't terrible. But if your ONLY hobbies cost money... well, your wallet isn't going to like that so much.
Instead, try to incorporate some FREE (or fairly cheap) hobbies! You'll keep yourself happy & busy without spending money!
Free / mostly free things to do:
reading (library books, obvi)
watching movies at home (Netflix, or rented from library)
painting/drawing (seriously, who didn't LOVE drawing when they were a kid? Now, when's the last time you drew something as an adult? I think that could be a fun activity!)
taking advantage of free stuff in your area (example for us: there's a public beach with free parking about 20 mins from our house!)
painting your nails
taking a cat nap (heh heh- get it? get it?)
hanging out with friends (somewhere free)
picnicing in a park (or in your backyard, or on your living room floor) with homemade food
freetetris.org (sorry in advance, it's addicting)
watching YouTube tutorials about how to cut your own hair, do your makeup, curl your hair, whistle, etc...
watching Jenna Marbles videos on YouTube. They kill me every time.