What do people do before they start a workout in a gym?
What do people do before they go out for a morning run?
What do people do before they start a zumba class?
What do people do before they start a dance routine?
Hopefully, you are noticing a trend in the response. Most smart people stretch and warm up before they begin any kind of strenuous activity. Yet for some reason amateur golfers do not seem to realize that golf is exercise and I rarely see them stretch or warm up their body. Instead, they show up to the course early for their tee time and start hitting balls on the driving range as their "warm up." What's worse? They jump right into their full swing and start whacking the ball. This is NOT smart and can be very dangerous.
Your body needs time to warm up and if you start swinging the club before your body is ready, you can pull a muscle or even tear something leaving you side-lined from golf until you heal. Stretching does not need to be a long ordeal and you can use your golf clubs as part of your routine. While it makes complete sense to focus on the upper body, don't forget about your lower body.
When you have completed your stretching, ease into practice swings on the range with a half swing. Slow your tempo, focus on the fundamentals while slowly working your way into a full swing. Once you feel comfortable increase your tempo, grip and rip it. This approach allows the nerves in your back to awaken without shocking your body with a big swing. A great swing has controlled tempo and rhythm. I think we can all agree that it is better to establish control at the first hole rather than the sixth.