First of all, we should learn from leg press, slowly press down at least 180, add 5 every week, and stick to it every day. Then you have to press your hips. It hurts to press the crotch. First of all, my legs are on the ground like frogs. Take a mat or a book or something, put it under your knees and press your ass there. Second, pull the waist. First lie on the ground with your legs together, and then let someone grab your arm and pull it back, keeping your head as close to your calf as possible. Former leg press is also very important. Sit up straight on the ground and bend forward. Don't bend your legs or bow your back. That's all. You can search for teaching videos from the Internet.