Fitness class recommendations?

I’ve lost quite a bit of weight pp, but I’m not healthy or in shape AT ALL! I’m at the point now where I’m actually borderline underweight. I need to build a little muscle and get a little healthier as well as get out of the house for a bit of me time (SAHM). I’d like to find a fitness class to take, but idk what I should do. I feel like anything high cardio I’ll just lose more weight and that’s not what I want. I also don’t want to do anything that’s going to kill me day 1, since I’m not in shape 😬.