Rafael Nadal has won 20 Grand Slam men's singles titles, including 13 French Open wins. He's finished the year as the No. 1 ranked men's tennis player five times. 

He's clearly one of the best tennis players in history.

And he also seems a bit, um, quirky.

Take liquids. Before a match starts, he arranges his energy drink so that it is slightly in front of his water bottle. He makes sure both labels face the court. When he changes ends, he sips his energy drink first, and then the water. Then he makes sure they're perfectly placed to line up with the end of the court he will play.

That's not all. He always carries one racket to the court. He always steps over the side line with his right foot. He always jumps at the net during the coin toss. He always takes off his jacket while facing the crowd. He always runs to the baseline to warm up.

It all seems a little -- OK, a lot -- OCD.

But not to Nadal. As he writes in his autobiograpy:

Some call it superstition, but it's not. If it were superstition, why would I keep doing the same thing over and over whether I win or lose?

It's a way of placing myself in a match, ordering my surroundings to match the order I seek in my head.

Science agrees. A 2006 study published in Journal of Applied Sports Psychology found that pre-performance rituals often benefit athletes, both to improve execution and to reduce anxiety and stress. (Which surely improves execution; we all perform better when we don't feel less tense.)

Those rituals aren't superstitious in nature. They don't confer some sort of magical power. 

Instead, they involve behavioral and cognitive elements that "intentionally help regulate arousal and enhance concentration and thus induce optimal psychological and physiological states."

Or in non-researcher-speak, a ritual can help ground you. Can help center you. Can help you regain and maintain focus.

In short, rituals can make you feel less stress -- which makes it easier to focus less on how you might feel, and more on what you need to do. 

For Nadal, that means always ensuring his tennis world is in order. As he writes, "When I do these things it means I am focused, I am competing -- it's something I don't need to do but when I do it, it means I'm focused."

For you, that might mean always placing two water bottles, a pack of tissues, and a notepad and pen below the lectern before you give a presentation. Or always having a client's order history up on your screen, always having a few key bullet points written down, and always writing "Slow down and listen" on the top of your note pad before you make a sales call.

Or anything -- even things that lack "direct instrumental purpose" -- that puts your world in order. Which then helps you feel more at ease. More self-assured. More in control. 

That signals you're about to "compete."

Just keep in mind that for behaviors to become rituals, they can't be random.  A 2016 study published in Organizational Behavior and Human Decision Process found that enacting rituals improves performance in public and private performance by decreasing anxiety -- but only if you think of the specific series of behaviors as a ritual. 

Because then you're signaling, to yourself, that you're preparing to do something important.

And that you're primed and ready to succeed.