This golf swing drill is so simple—and it fixes a really common backswing problem

Justin Rose has been playing so well recently that it sent me down a mini rabbit hole, which is where I found this interesting little video.

And now I want to try it.

The video is from Rose's offseason training camp at his home in the Bahamas. Golf Digest No. 1-ranked coach Mark Blackburn joined him down there for it, where they enlisted this simple—but effective—drill. I asked Mark about it and here's how it works.

First, you stand with your back facing the sun so it creates a shadow. Then place three golf balls in a straight line in the middle of your shadow.

• First ball should go where your belt buckle would be
• Second ball in the middle of your chest
• Third ball in the middle of your forehead

The goal is to make a backswing and make sure each part of your shadow stays over all three of those golf balls.

In Blackburn's words, it's a useful drill for Rose because it helps him "stay centered."

A common issue in amateur golfers' swings is that either their hips sway too far off the ball on the downswing, or their entire body moves towards the target on the backswing, also known as a reverse pivot.

In either case, your shadow would move off the golf balls.

You may notice that Rose's head dips below the top of the golf ball as he rehearses his downswing—that's normal. The important thing is that his upper and lower bodies are on top of each other here, which they are.

It's big side-to-side movement that you want to avoid. And strategically placing three golf balls just like this is an easy way to check.