Erik Weihenmayer has climbed the “Seven Summits,” the highest mountains of each of the seven continents. Almost everyone told him this was impossible. I recently interviewed him, and he told me: “You know, a couple of other people said things like I didn’t belong on the mountain or, like, anybody could get to the top of the mountain with 13 seeing guide dogs. I heard one guy say he was going to follow me to the summit and take a picture of my dead body just to make some money with the media. I call them naysayers. And, sure, there are naysayers, and I feel sorry for naysayers because they’re people who go around with the door in their mind shut, and it’s really more tragic for them.”

The reason why hardly anyone believed he could achieve his goal is that Weihenmayer was born with an incurable eye condition and has been blind since the age of 13. It’s been almost 20 years since he became the first blind person in history to climb to the summit of Mount Everest, an achievement that earned him a place on the cover of Time magazine. I asked him what mindset had enabled him to achieve his extraordinary goals. His answer: “I spend like 15 minutes just every day, envisioning myself standing on the summit, like, to the point where I’d hear the snow crunching under my crampons. I’d hear the slacks, I’d feel the sky, just feel the cold, and I’d feel the hearts of my teammates, I’d feel the tears, I’d literally start tearing up because I was there. And, when I summited Everest, I had already summited it 100 times in my mind. So, I think that kind of belief system and that kind of programming it into your subconscious is hugely important so that you can truly be there.”