hey Craig,
honestly if you're knees are bugging you, you should probably visit a physiotherapist or sports medicine (therapist) clinic. When I was younger (wisecracks welcome after this comment) my knees used to bother me some fierce - to the point where after playing a game of hockey, I was unable to stand up without "pulling" myself up. Turns out the cartilage was unusually rough and was causing pain through the normal range of motion. They provided me with about 10 stretches and a half-dozen strength exercises. Within a few months it was remarkably better. It was well worth the time/effort, especially in the long run.

"Chickens don't clap."