Dance? Maybe a course of swing dance or classic rock & roll - excellent for balance, timing as well as aerobic/cardio. Quite a few short courses around - and most you don’t need to bring a partner. Plus there’s the music aspect. And its a whole lotta fun.

I’ve never done yoga, but there are a lot of different kinds - some are pretty extreme physically and some are more meditative. Pilates is popular and there’s a lot of places around.