This article is going to show how u can do weight watchers for free, but first off, lets see why weight watchers is so successful. The 4 pillars of success; Food, exercise, behavior & support.
1 Hip muscles. Lunges work all of the gluteal muscles in the hips, primarily the gluteus maximus that is used to extend your hips. Taking large steps during a lunge can further engage this muscle. The gluteus minimus and gluteus medius are also used to stabilize your body throughout the lunge.  Thigh muscles.
Gluteals: there are 3 gluteal muscles that attach from the back of the ilium (hip bone) to the femur, which combine to extend/abduct the hip. When these muscles are weak, it can lead to poor knee control during squatting and lunging. Poor knee control can lead to poor mechanics, which encourage hip impingement.