Put your hands behind your hips and keep your body straight up. Keep this position for as long as possible. You can obviously feel the muscles of your hips exerting force. Then slowly return to the sitting position. Repeat this action for 3 times in each group, 15 times.
Of course, if you think it's too difficult to bump your ass, you can do it directly.
A relatively simple and convenient way to lift your hips, I hope I can help you!