Running isn't physical. It's mental.

Trust me. Any runner—especially the professional athletes—will back me up on this. Your mind gives up long before your body does. Even if you're in killer, elite shape, you can psych yourself off your best possible race. And if you're a beginner, your body will typically take you farther than your mind.

"Running is 80 percent mental." –Joan Benoit Samuelson, the first-ever women’s Olympic marathon champion

Proofs:

• What's the old saying? "A journey of a thousand miles begins with just one step." Countless days, I don't want to run. I talk myself into the first step by promising to stop after mile one or two if I'm still not feeling it. Know what? I rarely quit midrun.

• There are days when the entire miserable distance hurts. Even my skin aches. How do I keep going? I remember how good it feels to get the run done. And that the bad days are often followed by really, truly amazing days.

• Doesn't matter the length of the run—sprint, 10K, marathon—it feels like a long haul when you're in it. I may have run the route and the distance, but each fraction of a mile is a new experience. I need to keep in mind the big picture while remembering that getting through the here and now—no matter how hard it is—is the only way I'll reach my goal.

Perseverance is everything.

Running has toughened my mental endurance as much as my cardiovascular strength. The tricks my mind has honed through tough runs have gotten me through experiences that have nothing to do with running: brutal breakups, traumatic decisions, grueling business negotiations, friendships gone sideways, deaths of people I've loved, and family rifts.

Just like running, life is a mental game. Careers, relationships, marriage, parenting—and on and on? All long hauls. Want to succeed in making them the best they can possibly be despite setbacks, weeks you second guess it all, times you just aren't feeling it? Get through the moment with the big picture in mind, remember that good days follow bad days, and don't forget that sometimes the first step is the hardest.

You have more in you than you think. Believe.