I believe it is essential to challenge ourselves physically. I believe one of the best ways of doing this is through competition. Preparing for competition accomplishes many things. It gives us a goal; demands that we be organized, disciplined and following a plan.
As a word of caution, I would add that too many people equate athletic success with trophies, medals and age group victories. Those 'successes' are superficial and temporary. The real,deeper benefits are described below by the Australian athlete/coach/philosopher Percy Cerutty:
"Perhaps the greatest success is found when we achieve victory over ourselves. And that, perhaps, is the greatest reward that can be obtained from participation in athletics and sport, generally--the victory over our own nature, our weaknesses, our tendency, perhaps, to rush to alibis, palliatives, and excuses, rather than to admit our moments of weakness: of capitulation(surrender). So we come to the realization that the qualitative factor in success is purely personal, and that it is not something that can be measured only by the distance ran, the time recorded, the weight lifted or thrown, the height jumped, or the victories achieved over others. In this way success is subjective although the aims and ambitions may appear purely objective."