[old and tired]

Sport does not of itself have anything to do with the perfecting of the human being or with his destiny, and is of no assistance in attaining either, since excellence in physical attainments is quite compatible with a weakening of the subordination of these lower powers to reason.

To be truthful, your entire quote was probably over my head. But I think it's saying that physical pursuits are not, in and of themselves, virtuous. I agree with that. However, to be a great athlete you necessarily need a strong will to overcome physical obstacles (cramping, inclement weather, exhaustion, etc.)

Since so many of society's sins today are sins of the flesh, I really believe the pope is on to something terrific here. A teenage boy who is not physically exhausted at the end of the day is more prone to temptations than one who is. That's just common sense. But look around at the children (boys especially) you know and think if they get all the exercise they need to tire themselves out. By and large, the answer is no.

I for one am excited about this development and I have great hopes for the new Vatican Sports Department.

[Bellarmine]

To put it into language you might understand:

Overcoming cramps, inclement weather, etc., will not get you to heaven, overcoming sin will.