I know a lot of us have been the victim of our own Knee issues. I myself am one of them. So I sat down this morning terrified to do Level 2 of 30DS, and said to myself there has got to be a better way to make this better. So I found some useful information and amazingly it all draws down to stretching out your legs properly.
After I did my 30DS I sat down and spent more time stretching. More than what Jillian does, and I did it RIGHT after my workout. I tell you what the difference was amazing!!! My knee does still ache but its not near as bad!!!
I had to share this with you all so that you too can be relieved of this and feel like you're held back or what have you.
Here is a couple links, but really its all just stretching EVERY muscle in your leg.