There are many patients with osteoarthritis who have questions about this issue, and even some physicians are inconsistent in their statements to their patients. In fact, the issue should be understood dialectically. After developing osteoarthritis, it is best to continue using the diseased joint and not to stop using it because you want to protect the diseased joint. It is important to remember that prolonged rest and inactivity of the joint does not reduce symptoms or slow the progression of the disease, but only causes muscle weakness and more severe joint dysfunction. In that case, is the more activity the better? Not exactly. Many patients have misconceptions about this issue or follow the misguided advice of some doctors to “be more active and exercise more”, so they blindly go for long walks, dance, or even run or climb mountains, which often backfires and leads to aggravation. It is important to know that the joint cartilage of patients with osteoarthritis is already damaged and overwhelmed, and then to do these exercises is undoubtedly adding to the damage to the cartilage. At present, the damage to joint cartilage is almost irreparable, so, in layman’s terms, it is important to “save it”. So, should we be active or not? The answer is yes. There is nothing wrong with activity and exercise, but the key is what kind of activity and exercise to do. By activity and exercise we mean “functional exercise”, which can reduce joint pain and stiffness, improve joint movement, increase muscle strength and bone strength, maintain joint stability, and help increase self-confidence and maintain a good mental state. It must be remembered that the knee is a major weight-bearing joint with its own special characteristics. Patients with osteoarthritis of the knee should do more non-weight-bearing activities and exercises, such as swimming and bed exercises (active knee flexion and extension to maximum range in bed, straight leg raising exercises, etc.), less weight-bearing activities (such as running and climbing), and avoid squatting and kneeling exercise movements.