If an exercise seems easy, check your form. There is probably something missing, and it is probably your attention.
One exercise frequently given to physical therapy patients is called The Clam. The exercise helps you` learn to differentiate the ball and socket motion of the hip from the rotational movement of the spine and pelvis. It also helps to strengthen the gluteal and rotation muscles deep in the back of the hip. The Clam demands core strength, but most of all it requires attention.