Many people that experience knee pain assume that they have some sort of problem with the bones or ligaments involved. Although this might very well be the case, you shouldn't also rule out the role muscle tightness plays.
For example: if you experience an achy pain on the lateral (our outer) part of your patella (often referred to as the kneecap), your problem might be a tight IT band that is pulling on it. Think of the knee as a train that is meant to move only forwards or backwards on a track. Any sort of force that pushes the train to one side or another is going to impede its natural motion. Since the IT band runs along the side of your leg and the patella, tightness is putting constant pressure on the joint.
One simple solution is to self-massage the tight muscle with a foam roller. Here is Hussain's video demonstration, which will help you perform the exercise.
You can also use the foam roller to loosen other muscles that impact your knee, such as the quads and hip flexors. For a demonstration on how to massage a specific area, don't hesitate to ask one of our fitness professionals the next time you pay us a visit.