You’d be surprised at the life lessons you can learn running marathons. Back when I used to run them, I’d say that there is a moment at mile 20, when you know you have six more miles to go, where you have to make a decision. Six miles, 10 kilometers. That’s all you’ve got left. You’ve trained for a marathon. You’re staring down six miles.

Out of nowhere, your monkey brain starts going to battle with you. There is a voice in your head that celebrates: “You are going to do this. You are going to finish this. No matter what else happens in your life, you will forevermore be known as a marathoner. Run, walk, crawl, a finish is a finish. Yay, you!” And there is another voice in your head that scrambles around all Henny Penny-like, screaming, “Oh my god, what are you crazy? What were you thinking? Everything hurts, you are dehydrated, muscles are failing, you might pee yourself, or worse. You are going to die out here!”

Only one of those voices gets to win. And only you get to choose.

At Mile 20, the life lesson you learn is discovering what you are made of. Your brain will lie to you every single time. Let’s face it: running 26.2 miles is ungodly, unhealthy, and downright mentally unstable. And yet, it is a triumph of humanity that few have the mental and emotional fortitude to withstand.

You’ll notice I didn’t say physical fortitude. Here’s why: anyone — obvious injuries and health histories notwithstanding — can train to cover 26.2 miles. But not everyone can bring the heart to do it.

And, what else does your brain lie to you about? What other things do you quit because you just don’t know, you aren’t exactly sure, you worry it won’t work?

Your brain will lie. Your heart will not. Dig in, one foot after another, and keep on going. You got this.