Epictetus, Golden Sayings 118

Such a man needs also to have a certain habit of body. If he appears consumptive, thin, and pale, his testimony has no longer the same authority. 

He must not only prove to the unlearned, by showing them what his Soul is, that it is possible to be a good man apart from all that they admire; but he must also show them, by his body, that a plain and simple manner of life under the open sky does no harm to the body either. 

"See, I am proof of this! and my body also!" 

As Diogenes used to do, who went about fresh of look and by the very appearance of his body drew men's eyes. 

But if a Cynic is an object of pity, he seems a mere beggar; all turn away, all are offended at him. Nor should he be slovenly of look, so as not to scare men from him in this way either; on the contrary, his very roughness should be clean and attractive.