I think you're taking the argument to a moral extreme which really does not help much. You could say that reading, or thinking critically, are excruciatingly hard for some ... would you say that they should just give up on it, despite the benefits that it provides to a person?

The argument for exercising seems to be similar.

To be completely fair, I have a more visceral reason to agree with the OP in that I too have been quite alarmed by how obese some of my older coworkers are, and that has contributed pretty strongly to my desire to not be that way.