Because golf is a game of balance, you must equally train the golf muscles. Opposite the back are the chest muscles. The most simple exercise to start is the good old fashion push up. You may choose either the modified position or the military position. Its important to do each push up slow and controlled. The slower the exercise is executed the more strength you will build.
Lying on your back on a step or bench, place your feet atop the bench holding a dumbbell in each hand. Extend both your arms upward above your chest. Bending your elbows, move the weights away from each other and down until your arms form right angles. Then slowly return to the start position and repeat.
Standing with your feet shoulder-width apart and your hips rotated forward, place the Stretch Trainer parallel to the back with your arms extended downward. Pull on both ends of the Stretch Trainer taking out the slack, and slowly lift the arms upward feeling your chest expand and your shoulders stretch. Hold this stretch for 30 seconds and repeat.
Lie on your back with your knees bent and feet flat on the floor or on an elevated platform for support. Hold a weight in each hand and extend the arms upward. Rotate the weight to where your palms are facing one another. Bend the elbows slightly and slowly drop the weight outward to the side of the torso. Slowly return to the start position flexing the chest muscles and repeat.