On a clear afternoon in late October a few years ago, I stood underneath a giant overhanging cliff near my hometown, Lancaster, Pennsylvania. The scenery that day was particularly 1 , with deer chewing on the brown grasses by the river below, and hawks 2  the wind. 

I was tied in, ready to 3 . I was attempting to do a tough route for the first time. "Onsight" (首次攀登), as we call it, means I didn't know where I was climbing to. It would be a hard try for me to onsight such a difficult route. What I need is focus. No 4 .

Just as I was about to climb, 5 in my body, which I hadn't felt yet, woke up and said hello to me. That was a terrible sign for any athlete. Desperate as I felt, I painted a coat of 6 on my inner walls of doubt to ease my tension. I 7 myself at the top, celebrating. "You can do this," I 8 told myself. "If you believe, success is for sure."

It didn't work. 9 , I fell near the top. Defeated, I lowered myself to the ground and realized immediately that the too strong desire to climb the route had 10 me from doing it.

My self-worth was closely 11  at that unnatural moment with my success or failure, which 12  a chain of reaction: unnatural desire, pressure, performance anxiety. I had just climbed with a mind fascinated with the top but a body 13  below with irregular and unnatural movement. 

I told myself that on my next 14 , success or failure didn't matter. "Just make one move at a time." I gave myself a pass for whatever would happen. Case closed, it 15 . I floated to the top with grace, clarity and 16 .

That moment got me thinking, and then researching. At some point, I concluded this experience 17  simple arithmetic (算术): When I 18  (determination, self-confidence, desire), I failed; when I took away (the desire for success); my body moved with greater 19  and I made it. As an athlete of 30 years, I discovered the 20  of subtraction (减法) for the very first time.