According to the Titleist Performance Institute and trainers worldwide, your glutes (a.k.a. butt) are the king of the swing. And for most of you, they aren't working. With our sedentary lifestyles (e.g. sitting, driving) and our poor posture created over time, we move without using our full body. In effect, we bypass our butts.
The problem is... our butt acts as both a stabilizer and a power source. Huge surprise - those are both very important in a golf swing. You need stability to achieve consistent contact and you need mobility and power to hit the ball out of your shadow. Here's a short video on how to warm up that inactive butt and improve your golf swing almost immediately.