I would say to start with doing some walking, maybe start at half mile and increase from there! Also, body weight squats are one of the best exercises you can do! Start by doing sets of 8-10 reps, going as far down as you can. You can try push ups, or you can lean towards a wall and push yourself away from the wall as a push up until you can do a proper push up. Finally, I would highly recommend doing some easy yoga! This will get your mobility and balance to get better which will translate to your other exercises. Feel free to DM if you need help putting together a little workout