exercises to build strength in my knees

I used to have weak knees and found doing squats and riding an exercise bike really helped strengthen the muscles that support the joint so I am less prone to injury now. 

Just make sure you are careful with your form when you are doing squats. Your knees should point in the same direction as your toes and should not extend past your toes when squatting. Focus on pressing your heels into the ground and keeping your back straight. Hold your arms out in front of you or place a chair behind you if you need help balancing.

If squatting until your legs make a 90 degree angle is difficult or painful, just move through a smaller range of motion until you build more strength.

...and enjoy the added bonus of a perky butt:)