Good golf posture allows you to make a good golf swing. It makes it easy to achieve fullness of body rotation on both backswing and foreword swing. It allows your arms to swing freely in a path that goes towards your target at impact. It is good posture that dictates that the distance you stand from the ball is proper, so solid shots are struck.
In the course of an average day at Hilton Head National, on the first tee, the driving range or my lesson tee, I see a lot of people address golf balls in poor posture positions. Too bent-over tops the list, followed by, or combined with, reaching out with their arms, spine curved foreword, too much bend at the knees and face down so chin is on chest. Any or all of these really gets in the way of a good golf swing.
Golf is a game played standing-up, not crouched over. To begin, stand straight with arms hanging by your sides. Next, just start to sit down. This movement of your hips back and down will flex your knees slightly. Keeping your weight balanced evenly between your heels and the balls of your feet, tilt your spine foreword until your arms hang vertically about six inches in front of your thighs. This tilt should be from your hip sockets while keeping your spine straight from your tailbone to the top of your neck.
Add a golf club to your hands retaining the vertical hanging position of your arms, and sole the club. This gives you the correct distance to stand from the ball. Good posture, like a good grip, is something you can control to make you a better golfer. Be conscientious and consistent about getting it right!