Watch the video and see if you can improve your squatting pattern.
When you get more comfortable with squats, your knees and back will feel more stable and you'll probably be able to squat deeper - and they won't feel as hard!
Squats can still be a tough exercise, but a good pattern will make them a lot easier. And knowing when your quality and technique are failing will make it easier to figure out when to stop the set.
Getting better at squatting will improve the strength of your lower body for everything you do, so it pays to master this one.
Doug Barsanti
ReInvention Fitness
P.S. If your knees hurt during squats, 9 times out of 10, your thighs are too strong despite the common misconception that the knees hurt because the thighs are weak. Start learning how to use your hips and give those thighs a break!