Many people live with restrictive medical conditions that limit or prevent any level of "hard" exercise. Those conditions are certainly not of their choosing, and the underlying implication that those people are "guilty" of a lack of "discipline and intellect" is offensive and deprecating. The unfortunate fact is that such conditions become increasingly likely as we all age, becoming a near certainty for most people as they approach and pass 60.
That the parent commenter has evidently managed to avoid (thus far) that sort of misfortune is wonderful for them. But it shouldn't be used to demean or belittle those who have not enjoyed that good fortune.