At the age 23, Jordan Spieth became the youngest player to win the British Open since 1979. It almost didn't happen, but Spieth regained his mental edge with help from his caddie.

Through the first three rounds Spieth looked unbeatable, until the Sunday of the 146th Open championship. He walked up to the first hole with a three-shot lead and hit a booming tee shot. It was nice drive, but dropped in the deep grass on the left side of the fairway. Spieth was visibly upset when he walked to the ball and could be heard complaining to himself.

That's when his caddie, Michael Greller, simply said, "Get over it."

Griller added, "168 front," which is the distance Spieth had left to hit the front of the green. In three words--get over it--Greller was reminding Spieth to let go of the past failure and focus on the next shot.

Spieth faced another key moment when had to take a penalty on the 13th hole. He came back strong with a birdie and an eagle on the next two holes and won the tournament.

In a remarkable acknowledgment in the media center after the round, Spieth said the memories--the 'demons'--of his final round collapse at last year's Masters continued to haunt him. Even the best performers have a difficult time forgetting past mistakes, but the great ones find a way to focus on the future.

Forget past mistakes.

Golf legend Ben Hogan once said, "The most important shot in golf is the next one." Golfers make bad shots in every round. The champions forget the bad shots quickly and focus on the good ones. The same approach applies to any performance, including public-speaking.

I was working with a top executive of a large bank who had a paralyzing fear of public speaking. He had lost his place once during a presentation and experienced a small panic attack. He never forgot it. He kept replaying his worst presentation over and over again in this head, each and every day. Once he started his practicing repeatedly for the next presentations--without replaying the past--he grew to enjoy public speaking again.

According to one of golf's most famous mental coaches, Bob Rotella, "There's nothing worse than dwelling on the putts you've missed. It's psychologically no different from actually going out on a green and missing them again, over and over." In other words, by replaying mistakes whether it's a golf putt or a business presentation, you are literally training your brain to do the same again.

Jordan Spieth's caddie, a former school teacher, once said that part of his role is to be "a calming influence, an encourager." Most of us don't have a caddie by our side to boost our confidence when we replay past mistakes--and we will replay our past mistakes.

But we can still take a lesson from how the best caddies and players do it. They give themselves ten paces to shake it off, and focus their concentration on the next shot. If they don't get over it, tension will creep into their next swing. Nothing ruins a golf swing more than tension and it will ruin a presentation, too.

When you watch a great speaker, he or she seems relaxed, at ease. They don't appear "tight." That's because, like great golfers, they've practiced and done all they can to prepare. The only thing left is to enjoy the process.

If an executive I'm working with is about to give a major public presentation, I'll often send that person an email or text: "Put a smile on your face, have fun, and rock it!" Smiling, relaxing and having fun should be the last "swing-thought" you have before launching your presentation.