Don't skimp on the stretches and don't push too much past your comfort zone.
You might also try taking some glucosamine/chondroitin supplements, and take a look at your diet to make sure it's not too carb-heavy, and switch away from vegetable oils in favor of extra virgin olive oil (these will help reduce inflammation).
i'm already low carb, and I;'ve got glucoasime/chrondoitin tablets but don't take regularly. Also do stretches as advised. I've been doing research and I think its from not having proper landing from when doing plyometrics.
When did Tony say that? I'm doing a lot of Insanity these days so I really hope I'm staying safe, e.g. trying to engage my muscles as much as I can during landing, not twisting my knees.
He said it when he came on Attack of the SHow on G4TV. I'm not blaming insanity or anything cos Insanity even advises this is not for beginners, and plyometric exercises should only be done after you have good base in fitness and make sure there are no muscle imbalances in your legs. From the research i've been doing I suggest you have a really good pair of cross fit shoes, with good padding, good surface to land on, and proper landing from jumps (land on the balls of your feet), full squats meaning you go to atleast your knees.