John Chrysostom, on 1Cor 9:24

Having pointed out the manifold usefulness of condescension and that this is the highest perfectness, and that he himself having risen higher than all towards perfection, or rather having gone beyond it by declining to receive, descended lower than all again; and having made known to us the times for each of these, both for the perfectness and for the condescension; he touches them more sharply in what follows, covertly intimating that this which was done by them and which was counted a mark of perfectness, is a kind of superfluous and useless labor. And he saith it not thus out clearly, lest they should become insolent; but the methods of proof employed by him makes this evident.

And having said that they sin against Christ and destroy the brethren, and are nothing profited by this perfect knowledge, except charity be added; he again proceeds to a common example, and saith, "Know ye not that they which run in a race run all, but one receiveth the prize?" Now this he saith, not as though here also one only out of many would be saved; far from it; but to set forth the exceeding diligence which it is our duty to use. For as there, though many descend into the course not many are crowned, but this befalls one only; and it is not enough to descend into the contest, nor to anoint one's self and wrestle: so likewise here it is not sufficient to believe, and to contend in any way; but unless we have so run as unto the end to show ourselves unblameable, and to come near the prize, it will profit us nothing. For even though thou consider thyself to be perfect according to knowledge, thou hast not yet attained the whole; which hinting at, he said, "so run, that ye may obtain." They had not then yet, as it seems, attained. And having said thus, he teaches them also the manner.