Workout suggestion — a workout to strengthen muscles for sit to standing

I’m 61 years old and can no longer get up off the floor from a cross legged sit. When I try to sit down this way I plop down, using gravity, to get to the floor and then I can only lift my butt about 3 inches off the floor and can go no further. I would love a video or series of videos to strengthen the muscles needed to go from sitting cross legged to standing.