He gave me one exercise of laying on my stomach and having someone bend back my knee to help strengthen my thighs.
This will not help to strengthen your thigh muscles but will help with your bend. Whenever anyone is pushing or pulling on your leg, you are not using your muscles to do it yourself. This isn't helpful. That's why we always suggest no hands on the leg! It can also cause your knee to bend further than it's ready to be bent and will cause harm. Just do it yourself and you'll be helping your knee and leg more.