The very young often encounter things that are too hard for them. Within just a few years, however, a young person at the peak of his or her mental and physical capacities can feel that nothing is too hard—but all too quickly we learn of our limitations.
I'm sure that most of us have experienced that feeling of invincibility during our youth. But life goes by quickly and our physical prowess fades. Professional athletes begin to wane, and the end of their athletic careers comes into view as their bodies age.