Something called Insanity probably is.
When I had problems with my knee, I saw a doctor and got into physical therapy. Knee problems have a variety of causes and it's best to let a doctor diagnose it and help you decide which exercises you can do. I had to have physical therapy. The therapist suggested 4 exercises for me: Walk on LEVEL ground, do low impact aerobics in a swimming pool, do lap swimming; or use a stationary bike.
Now, after several years of following that advice, I have decided to try a low impact Zumba, one for older or injured people. There's no jumping. Zumba has twisting in the knees and ankles, and it's important to wear the right shoes. A dancing fitness shoe works because it's smooth on the bottom whereas walking/running shoes do not work well as they tend to grip the floor and can cause injury.
Keep in mind what my doctor told me. For every pound you take off your total weight, you take several pounds of pressure off your knees.
"The only way to hurt your body is to not use it." Jack LaLanne
| current weight: 140.2