Rick Ankiel wasn’t the first baseball player to forget how to throw—in fact, the phenomenon is sometimes called “Steve Blass Disease” or “Steve Sax Syndrome,” after other baseball players who suffered sudden-onset throwing challenges. It’s not unique to baseball, either. In 2008, an introverted twenty-year-old tennis player named Ana Ivanovic won the French Open and became the top-ranked tennis player in the world. Commentators imagined her winning “a host of grand slams,” and maybe even becoming a formidable rival to all-time great Serena Williams.

But shortly after that French Open title, Ivanovic began to experience the yips—not when hitting the ball or swinging the racket, but when tossing the ball before serving. From footwork to swing mechanics, tennis requires precise movements and profound bodily coordination. Throwing the ball straight up in the air before serving is just about the only part of tennis that isn’t difficult. But when Ivanovic began to experience the yips, her hand would jerk mid-toss, and the ball would drift to the right, or too far forward.

Former tennis pro Pat Cash described watching Ivanovic’s serve as a “painful experience,” and it truly was, but if watching it is a painful experience, how much more painful to be the server, unable to toss the ball the way she had her entire career, ever since she first took up tennis as a five-year-old in Belgrade. You could see the torment in her eyes. Watching someone struggle with the yips is like watching a school play in which a kid forgets their line. Time stops. Attempts to disguise the discomfort—a little smile, a wave of apology—only heighten everyone’s awareness of the anguish. You know they don’t want your pity, but you offer it anyway, which only furthers the shame.

“She has absolutely no confidence in herself,” tennis great Martina Navratilova said of Ivanovic, which was no doubt true. But how could you be confident?

All serious athletes know the yips are possible, that they happen to people. But knowing something abstractly is different from knowing it experientially. Once you’ve known the yips personally, you can’t unknow them. Every time you toss a tennis ball for the rest of your life, you’ll know what could happen. How can you regain confidence when you know that confidence is just a varnish painted atop human frailty?

Ivanovic once said of the yips, “If you start thinking about how you come down the stairs and think about how each muscle is working, you can’t go down the stairs.” But if you’ve fallen down the stairs, it becomes impossible not to think about how you come down the stairs. “I’m a person who overthinks and overanalyzes everything,” Ivanovic went on to say, “so if you give me one thought, it creates a lot more.”

The yips have many names—whiskey fingers, the waggles, the freezing. But I like “yips” because it’s such an anxious word; I can almost feel the muscle twitch inside the word itself. The yips are most common among golfers. Over a third of serious golfers struggle with them. Golfing yips usually appear when golfers are trying to hit putts, and people have tried all kinds of cures to stop the spasms. Right-handed golfers might putt left-handed, or they might try unconventional grips, or long putters, or short ones, or bending over the club and anchoring it against the chest. And the yips don’t only affect putting. One of the world’s leading golf coaches can only effectively swing a driver while looking away from the ball.