May I suggest simple crafting, like whittling, ancient/native pottery, wood carving, paper basket weaving, origami, crochet (or the slightly more addictive and expensive knitting), braiding, weaving, macrame, yarn spinning, decorative knotworking, flower pressing, dyemaking, hand dying, flower arrangement, make walking canes, etc?

Or maybe an instrument? Someone mentioned guitar, but why not harmonica, ukulele, bongos, simple percussives, or why not take up singing, there's typically a choir almost everywhere, or you could try solo, or whistling, or yodeling.

Or maybe take up gardening/growing? In pots, hydroponically, maybe on a growing lot, or someone's yard?

Or take up community projects, like either sanctioned or guerilla gardening, greening, forestry, litter picking, maintaining communal spaces, volunteer, start a community project (pollination diversity, bee keeping, growing lots, food drive, food forestry)

Or take up a cause? Build community, take affirmative action, demonstrate, protest, coordinate, communicate, with an established org, or on your own?

Maybe the outdoors could entice? Take up walking, ornithology, watch bats, discover new insects, take up chabana/ikebana, learn to forage, learn survival skills, go hiking, stack rocks, track animals, learn trapping, get into scouting, make bark boats, learn to skip rocks, climb trees, jump in puddles, pretend (or practice) animistic rituals, feel rain on naked skin, sleep under a bare sky, pick skulls, horns and bones to craft with.

Perhaps create stories, tell stories, write poetry, learn magic, juggle, poi, take up clowning, go swing/country/folk/traditional/ballroom/social dancing, try Butoh, write sketches, join a theatre, start a business, take up decorating, or just embrace whimsy?

I can also warmly recommend trying a new thing every week/month/period and see what sticks and not.