Here's a quote found by a coaching friend from "The Inner Game of Tennis". I, like he, find it to be very profound and directly applicable to thinking about the development of a young football player.

"When we plant a rose seed in the earth, we notice that it is small, but we do not criticize it as rootless and stemless. We treat it as a seed, giving it the water and the nourishment required of a seed. When it first shoots up out of the earth, we don’t condemn it as immature and underdeveloped; nor do we criticize the buds for not being open when they appear. We stand in wonder at the process taking place and give the plant the care it needs at each stage of its development. The rose is a rose from the time it is a seed to the time it withers and dies. Within it, at all times, it contains its whole potential. It seems to be constantly in the process of change; yet at each state, at each moment, it is perfectly all right as it is. Similarly, the errors we make can be seen as part of the developing process."