It's good for your game
Remember to look good to feel good
Assuming the correct golf posture will not only improve your golf shots, it also will affect how you think about your game and yourself. And having confidence in yourself is at least as important as good swing mechanics. As my coach used to say, "If you look good, you feel good, and if you feel good, you do good."
Correct Golf Posture
Assume your address posture and then use your golf club to check two key relationships that create a perfect setup:
1. Flex your knees.
I've laid the shaft over my right thigh in the first photo here so it runs to the tip of my foot, creating the correct amount of flex. Too much flex and I'll have to rise up through impact, catching the ball thin. Too little flex forces the opposite, a drop down and a fat shot. Note that the correct golf flex is about the same as your normal walking flex.
2. Perfect balance at address and while you swing.
In the second photo, I've taken my address posture and then, while keeping my right arm in place, I've run the shaft from the tip of my shoulder through my elbow so it touches the tip of my knee. The shaft should hang straight, and you should adjust your body until your shoulder, elbow and knee all line up.
When I create an athletic posture, it looks as if I could jump across a pit of snakes without even changing my original body posture. I'm so ready to go that I could jump with no crouching needed.
The Takeaway: At high swing speeds, compensations made due to bad posture promote big-time inconsistency. The correct golf posture at address allows me to stay in position so my spine angle and knee flex at impact match address. Because my posture is correct, I feel confident, and that's a good feeling to have when you're playing golf.