Training for a half-marathon—or any race—gives you a lot of time to listen to the mind-monkeys. The ones that remind you to pick up the dry cleaning; buy eggs, bread, face soap, and 409; call back your sister; and tell yourself you’re slow and not capable of running another step, let alone 13.1 miles.

While the mental to-do list won’t do anything more than annoy you like a swarm of mosquitoes, the negative internal monologue can be destructive. Silencing those pesky monkeys can be harder than going the distance.

A better alternative? Drowning them out with a mantra.

As you probably know, a mantra is basically a positive sound or phrase that people repeat over and over—and they are not just used by yogis trying to reach bliss. Many elite runners use them.

Sports psychologists, as well as other experts, believe the repetition of a word or phrase results in a reduction in stress and an increase in well being.

Focusing on saying a mantra gently draws attention away from other thoughts —“my quads are killing me,” “will I ever reach the next mile marker?” or “why am I doing this again??”—that may be otherwise causing you to doubt yourself.

How do you find a mantra that speaks to you?

• Choose something short and simple. In other words, stay away from words that are more than two syllables and sentences more than five or so words long. “I’m an energetic and courageous running machine” might be more of a mouthful than your mind can handle by mile 11.

• Pick something that has meaning to you. “Rock it!” might spur you on, while it makes your running partner think of tripping and falling—or a bad 80’s hair band.

• Have a few mantras in your arsenal, such as one to ease pre-race jitters (“calm and cool, calm and cool”) and another to fire you up in the later miles (“I’m awesome! I’m awesome!”)

• Consider words that give you instructions in addition to motivating you. “Fast feet!” or “Strong arms!” both help you get the job done. A bonus of those two simple phrases? You can say them rhythmically, one word with each footfall or arm swing, to keep your pace up.

• Crib lines from a favorite song, especially an anthem on your racing playlist. Some ideas: “I want more!” from “My Body” by Young the Giant or the Black Eyed Peas’ chant, “Let’s do it, let’s do it!” from “I Gotta Feeling.”  (Meanwhile, stay away from lyrics like Maroon 5’s “Harder to Breathe.”)

• Practice it before race day. On a run where you’re not feeling great, trot it out and see if it works for you. If not, head back to the mantra board to pick another.

Before you head out on race day, remind yourself of your mantra, and how it can get you through the tough times. The starting line, which is always atwitter in excitement and energy, can be a nerve-wracking place. Pull it out while you’re standing still, if need be, and get focused on the task ahead.