A: "Watch your form, always stretch postworkout, and give your legs ample time to rest."

First, make sure your form is correct for each repetition.

Squats:

1. Your knee should not go past your ankle.
2. Legs should be shoulder-width apart.   
3. Push your bottom out while keeping your chest up when performing squats. You should act as if you are sitting down.

Lunges:

1. Your knee should not go past your ankle.
2. Your back leg should be set out a little bit wider, not directly behind you, for balance and control.

Then, make sure you are using the right amount of weight. Using too much weight can increase knee pain, so try using your body weight alone to do squats or lunges. However, incorporating some weight increases the intensity level and muscle resistance, and also builds muscle tone, so hold light weights, if you can do so without pain.

Always stretch after workouts, and give your legs and knees time to recover before training them again. If you are still experiencing pain, listen to your body. If your knees continue to bother you while doing squats and lunges, stop doing them and consult your doctor or an orthopedic surgeon to rule out any injuries.