A recent study suggested that meniscus surgery doesn't help. Studies can be misleading. Even small losses of meniscus tissue lead to big changes in force concentration on the tibia (shin bone) and eventually arthritis.
Exercise for fun, or for training, or both. Exercise wisely, in ways that help you in sports or your daily life. But don’t do exercises that are useless, or potentially injury-generating. Here are a few doozies that should not be on your list: