In the summer, I ride a bicycle. A few years ago, I was training to ride across California’s Death Valley. A friend of mine, Johnny, spent the summer training with me. Together, we rode a “century” (100 miles) almost every Saturday. Once, we rode 107 miles in the rain. Johnny never complained — not once.

One miserably hot Saturday, we were riding through the hills of southern Ohio. One hill in particular was brutally steep. I really wanted to get off my bike and walk, but I held in there, barely turning the pedals over. Meanwhile, Johnny was falling farther and farther behind.

A couple of cyclists rode up, and one of them said, “Hey, you need to wait up for your buddy. He’s really struggling.” I said, “Thanks. He’s fine, though.” The cyclist persisted, “You should really wait.” I said thanks again and kept on pedaling. These cyclists were clearly disappointed I decided not to wait for my buddy. But I had spent all summer riding with Johnny, and I knew I didn’t need to wait.

A little later on, the cyclists looked up, surprised to see Johnny barreling past them, with me barely hanging on to his rear wheel. Johnny doesn’t look like a cyclist or an athlete of any kind, but he’s tougher than nails. And when he gets his second wind, it’s a sight to behold. I told him what had happened, and he gave the cyclists a big grin as he flew past them.

Cycling, like many things life, is a mental game. When the little voice inside your head tells you you’re done, that you can’t go on, that is when you know you’re really just getting started. That little voice tries to make it easy to quit. It tells you that you’re tired. Sometimes it’s clever enough to persuade you to never even begin, that there’s always tomorrow…

But here’s a radical thought: You don’t have to listen to that voice. You are much stronger than you think. You can go much further than you’ve ever imagined. If you persist, you will get your second wind — and your third and your fourth.

Sometimes, you may have to shift gears and move slower than you’d like. But when your second wind kicks in, you can put the chain back on the big ring and pedal like there’s no tomorrow. Just keep turning over those pedals. You’ll make it up the hill.

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S. Anthony Iannarino is the managing director of B2B Sales Coach & Consultancy, a boutique sales coaching and consulting company, and an adjunct faculty member at Capital University’s School of Management and Leadership. For more information, go http://thesalesblog.com/s-anthony-iannarino/