I'm only semi-joking, but perhaps join an obstacle course race, or a gymnastics class for adults. I've done both, and it's been so much fun. The obstacle course is all kinds of weird things you have to climb over and under (I'd avoid the mud variants, unless you like that aspect, though). And even though I never did gymnastics as a kid and am stiff as a stick, it was great fun to play around in a big hall with other equally bad adults trying to do gymnastics, climb ropes, forward rolls, jump into foam pits etc.

Like being a kid again.