Your ability to shift your weight in the golf swing is determined by the amount of glute strength you have. If those muscles are weak, the tendency is to use more upper body muscles to create the downswing which could lead to swing faults and injury. Strengthening your glute muscles will help put power into your swing. This exercise will strengthen your internal and external hip rotators.

Place band just below your knee caps and get into a semi-squat stance.
Widen your stance so that you create tension in the band.
Keeping the sole of your foot planted on the ground press your right knee outwards and the inwards. Try to drive knee out as far you can and then press knee in moving your hip.
Do 12 to 15 repetitions on each leg.