I took up climbing in my mid-30’s (I’m now in my late 30’s). I find the addition of the mental problem solving component really helps the gym fatigue. It’s a good upper body, core, and cardio workout (though I do try to do pushups and bodyweight squats on days I’m not climbing in order to hit the muscle groups climbing doesn’t), and excellent grip strength has a lot of practical benefits.

This doesn’t fit your time constraint (it’s more like an hour or two a few times a week), but I find the social and mental aspects mean it’s not just “exercising” and the time investment is worth it.