In my spare time I try to learn to do all the things I’ve always wanted to do just lacked the money, discipline, time…
Paint, buy some cheap paints and dabble
Write poetry
Sew, take something old and make it new
Look at a tree in your yard and try to see how many different colors of green there are
Stargaze
The dirt doesn’t even have to be outside. Houseplants can be fun, and you can grow nice ones with things from a trip to the supermarket - citrus fruits, fresh ginger, black pepper, poppy seeds, … (Some spices might be irradiated to kill bugs. That kills the seeds too. Try a natural-food store if supermarket spices don’t work.)
Tie knots. No, not macrame, but traditional sailor’s rope-work.