I was about 16 years old and, as I've said before, had no clue about what martial arts was about. I'd never watched any martial arts movie or even heard of Bruce Lee. A buddy got me into TKD by telling me it was, "like boxing but you kick people." Well, I still remember one of my first couple of lessons. Instructor, Pat Little, had us standing after a workout one day and he told us to hold our arms out to the sides, make fists, and imagine that we were holding buckets in each hand. Heavy buckets. Five gallon buckets filled with water. We were told to imagine the weight as unbearable. He walked around us talking to each of us as we held our arms out. Pretty soon we were all convinced that there was no way we could hold up our arms. One by one we began to surrender and collapse.
After a couple of minutes rest and shaking it off, we repeated the exercise, but this time the verbal cues were different. We were to imagine strings tied to our arms holding them up. Imagine that our arms were hollow and weightless, filled with helium. Cool breezes blowing upward helping us hold. Soft pillows propped under our arms so that it was no effort to hold them up at all. You guessed it. We all sustained the posture much, much, much longer the second time.
So, what was it about this simple, almost trite, demonstration that was so memorable, even so many years later? This was perhaps the first time I'd heard the moral of this exercise and had it so clearly linked to a practical, physical thing: "The mind drives the body. The body serves the mind. Change your mind and you change what you are physically able to do."
And that is one of the most amazing things about the martial arts. Learning to change how you think about your circumstances in order to change the circumstances in your favor.