To make your leg and pelvis muscles stronger, practice squats. Stand with your feet slightly wider than your hips with your toes pointed forward. Bend your knees and send your bottom backwards, as if you’re sitting down. Keep your weight in your heels and your arms either out in front of you or on your thighs. Raise back up and repeat 10 times.
If that proves too hard, you can try to slowly sit in a chair from a standing position without using your hands.