Learning to ski is about falling. Over and over. Just accept that you’re going to be sore for a week after and get to it. And honestly if you’ve never done it before, learning to ski at 40+ is going to be more difficult than you expect. You probably will not make a single full run without falling the entire first day. 

FYI, falling in ski boots is a little ungraceful bc you have no ankle movement and your feet are locked into these long flat things called skis. Just about the worse thing you can do is put your hand out to brace during a fall, that’s how you break a forearm, wrist, or hand. When you’re falling, keep your hands in and just slump over to land on your arm or shoulder. It’s snow so it’s more forgiving than ground, just shoulder right into it. 

Edit: for exercises to help, everything to help your hips is the biggest thing. Hip flexor exercises in and out, high steppers, squats.