My secret to surviving the Tokyo marathon last year was not finding the perfect pair of shoes, fuel, or training plan. All of these were important, as were proper hydration, a motivating playlist, and chafe-preventing lube. But what really kept me going each time I wanted to give in to my legs’ threats to fall off if I didn’t stop? A smile.

Call me crazy – which isn’t too far off a character judgment for anyone who celebrates winning a lottery (then paying) to run 26.2 miles — but flashing your pearly whites rewards you with a surge of optimism that really helps. Last year, I shaved over 15 minutes off my first marathon time.

Still don’t believe me? Smile right now. Don’t let your cheeks slump yet! Hold that dashing grin and look around. Chances are that if someone else saw you smile, s/he is now smiling too, sparking a chain reaction that’s shifting the mood of the room.

The truth is, we can’t help but feel better. As the title of Sarah Stevenson’s Psychology Today article suggests, “There’s Magic in Your Smile.” Fireworks go off in our brains when our lips curve upward, chemical reactions that produce endorphins that not only make us feel happier, but also less pain. While there are many other benefits you can read about here, these two alone work wonders while running, whether you’re racing in the Tokyo marathon or going for your first walk-jog.

I’m not going to lie. Smiling will not make your feet sprout wings that will carry you effortlessly through the rest of the race. You will hit the infamous “wall.” In fact, if you’re like me, you’ll hit the wall not at the 20-mile marker, but various times throughout the race. The key is knowing that you’re going to hit waves of exhaustion that will roll over you and then pass. Each time this happens, smile, knowing you’re stronger than you thought you were just seconds before, a lesson that I have carried with me long after crossing the finishing line – you ran 26.2 miles, of course you can face this…and this…and this…

But smiling requires effort that’s hard to put forth when you’re struggling to even take another step. Here are 7 tips to smiling your way through the pain:

1) Say cheese: Pretend like you’re having the time of your life whenever you pass a professional behind a lens. You don’t want your friends to say that they saw you on TV and didn’t know by your ghastly expression whether to laugh or fear for your life.

2) Build a meaningful playlist: I try to run as long as I can without music. A sort of delay of gratification that makes that first song that much more enjoyable. Last year I asked my loved ones for suggestions – what are the songs that get you pumped? When I heard their recommendations, I couldn’t help but think of them and smile, suddenly transported to a time we listened to the song together. No longer was I running the marathon, but laughing with friends over a bottle of wine or better yet dancing in Vegas. Even if only in mind, I couldn’t help but crack a smile.

3) Don’t hold back high fives – Strangers came out to cheer YOU on! At least that’s what I tell myself. Though the crowds are not really standing for hours in the winter chill for my sake, they still get psyched whenever runners respond to their cheers. Every time I slapped a slew of hands held out on the sidelines, like osmosis, I somehow absorbed their excitement and energy – a much-needed reminder that what I was doing was in fact exciting!

Which brings me to the next tip —

4) Feel lucky— Think about it this way: Over 300,000 people entered a lottery to do this crazy feat and you are one of the few (about 12%) who actually earned this chance to cross the finish line! Motivation resparked, smile and run on.

5) Be in the moment – Like all things, this too will pass. Though at points you will feel like you’re never going to finish, you will, and soon this remarkable experience will be over. Now that’s something to smile about! Toward the end, when tears threatened, I realized that the only way to finish was one step at a time, one breath at a time. I focused on each inhalation and each exhalation, repeating this phrase in my head, which brings me to the next tip…

6) Recite a mantra — Repeating words of encouragement boost your self-confidence and thereby your determination to forge ahead. Plus, they give you something to sync your steps to, getting your feet back into a groove. Whenever I hit an energy lull, I repeat the ideas I aim live by –“Grace, peace, strength, love, you’ve got this, you’ve got this,” I recite in my head and sometimes, in really desperate time, aloud. “Don’t tell people you actually say that to yourself!” my husband said when I revealed my mantra. So what if it’s incredibly cheesy! Somehow it works. I even cheer on my legs, “Ladies, let’s do this!” Laughing at myself, at all these silly antics (dare I admit I have more?) is another way to turn that fixed frown upside down and run on.

7) Catch a smile, spread a smile – There will be no shortage of smiles on the sidelines from cheering fans. It’s not easy to celebrate strangers’ steps for 4+ hours. Returning their smiles will keep the crowd pumped, and you never know, another runner struggling beside you may see your smile and follow suit. This ripple effect may just make it back to you when you desperately need that surge of optimism, that silent signal to gambatimasu!