Championship golf can be an exercise in cruelty.

Athletes in other sports have the luxury of unconsciousness. Even when they initiate the action, they spend much of their time in a state of unthinking reaction, relying on instincts honed by thousands of hours of practice.

They can often deal with nervousness or frustration or anxiety by hitting something or someone, sometimes harder than absolutely necessary.

Golfers live in a different world.

The performer stands alone, exposed, visible to his competitors and to the audience alike.

He has plenty of time to think about what he has done and what he needs to do. The physical action of swinging a club takes up less than two minutes of a four-hour round. The rest is walking, waiting, thinking, trying to maintain his internal equilibrium in the midst of a swirling drama playing out over a vast external canvas.

The results can be ugly.

On Saturday at The Players Championship, 28-year-old Kevin Na battled his inner doubts on nearly every tee. He fidgeted. He waggled. He stepped up to the ball, then stepped away. He began his swing, then swept the club far over the ball to indicate he had no intention of hitting it.

Somehow, he carded a 68 to take a one-shot lead into Sunday's final round. But his comments afterward made it hard to imagine the results would continue to belie his angst. (I thank the invaluable asapsports.com for its excellent work providing transcripts from major sports events like The Players.)

"I'm trying to get comfortable with my waggles," he said of the wristy partial swings that nearly all golfers take before bringing the club back in earnest. "It's usually a little waggle, half-waggle, little waggle, half-waggle, and boom, supposed to pull the trigger. But if it doesn't work, I've got to go in pairs. So it'll go four; and if it doesn't work, it'll go six; and after that, just - there's a lot going on in my head."

The assembled media laughed, and he went on: "And it's not - I'm not being nice to myself, trust me. I'm ripping myself. But there's so much on the line, I just have to sometimes back off. Or I'll force myself to take it back, and on the way down I'll come up and pull up and go over the top. As ugly as it is and as painful as it is, believe me, it's really tough for me, and I'm trying."

This is not a formula for long-term success on the PGA Tour, and Na knows it. Asked about the mental high-wire act involved in battling a tough golf course while "kicking your own ass in the process," Na spoke with surprising frankness.

"Yeah, it's pretty high-stress," he said. "I mean, after I get done, I'm pretty tired because there's ... not only am I grinding for the golf tournament, but I'm fighting within myself in my mind and trying to play a round of golf without backing off, without all this extra thing going on.

"And trust me, you know, I get ripped, a lot. I know TV, Twitter and fans are tired of me backing off. But you know, I'm ... I understand people being frustrated with me backing off, but all I can tell you guys is honestly, I'm trying, and it's hard for me too."

It's hard not to feel sympathy for Na, going through these gyrations in such a public way. But Na's struggles do not take place in a vacuum. His delays and hesitations slow the round for his playing partners and anyone behind him. If he refuses to hit a shot until he is absolutely ready, he creates a distraction for others in the competition.

"Yeah, I know guys make ... in the locker room or in the trailer, guys will be like, ‘I've got to play with you today, I've got the short straw,' " he said. "But they mean it to a certain point. ... [A]ll I can do is just be respectful and try my best."

But sometimes those last two concepts are in conflict. Slow play is a plague on golf in general, and it behooves the pros to set a better example rather than declaring, "I'm trying to make a living here, and I'll do whatever I need to do to play my best." The PGA Tour has the power to assess penalty strokes for slow players, but no tour player has gotten such a penalty since 1992.

On Sunday, Na birdied the second hole to extend his lead over Matt Kuchar to three shots. But after bogeys on Nos. 5 and 6 (and a Kuchar birdie on 4), the two were tied. When Na backed away from a short putt - something he had not done Saturday - and missed it for a bogey, it was apparent that the voices in his head were now questioning even the strongest part of his game.

Na made six bogeys over a nine-hole stretch, leaving the battle for The Players Championship to others. But no matter how much a golfer may be reeling, there is no referee to stop the fight before the finish. He made an effort to play with less hesitation, and he and Kuchar managed to keep pace with the players in front of them.

Kuchar won the tournament, smiling and outwardly calm despite whatever may have been going on inside. Na's deepest doubts were on full display, and he finished tied for seventh. Championship golf is a test of many things, only a few of which are physical.