Having good separation between your upper and lower body facilitates greater speed and power in your golf swing. Limited separation can result in a number of swing faults including too much lateral movement (sway or slide) and loss of posture.
Side Lunge with Twist-
Stand holding an exercise ball, golf club or hand weight with your arms extended and your feet together.
Side lunge to one side, keeping your flexed knee over your foot and extending the opposite leg.
Keeping your arms extended, turn the ball twisting your upper torso over your flexed leg.
Return to the start position and repeat on the opposite side.
Do 8 to 10 repetitions on both sides.
This exercise has all the elements of a good golf swing, including rotation, change of directions and stabilization. This exercise will also help you create that separation in your upper and lower bodies and will help increase cardiovascular endurance.