Im in desperate need of a hobby that will fill up my spare time so im not going out and spending money?

im in desperate need of a hobby that will fill up my spare time so im not going out and spending money that i should really be saving. i dnt knit or anything lik that and nor do i want to start. im not much of an artist so crafty stuff isnt really an option. im not into sport, apart from dance. i do enjoy writing and learning. ive thought about doin a self taught course of some kind, even if it is just to fill in time and not to pursue. i spend alot of time on the computer or decorating my room or reading and writing. i dnt want a hobby that will cost money because im trying to save. can someone please help me!!!!