Taken from Memorabilia III, XII
One day Socrates noticed that his friend was out of shape and said;
“Epigenes it looks like you are in need of exercise”
His friend replied that he wasn’t an athlete. Now since they lived at a time when Athens fought the occasional war with their neighbouring cities, Socrates replied that even if Epigenes wasn’t an athlete he should still consider getting into shape. He said it’s the lack of fitness that many men lose their lives in battle or save it disgracefully by turning coward and fleeing or being taken prisoner. Of the fit ones he said;
“And yet what has to be borne by anyone who takes care to keep his body in good condition is far lighter and far pleasanter than those things subjected to the out of shape person”
“the results of physical fitness are the direct opposites of those that follow from unfitness. The fit are healthy and strong, and many as a consequence save themselves decorously on the battle-field and escape all dangers of war; many help friends and do good to their country and for this they earn gratitude, glory and honor that leads to a better life and provide their children a better means of achieving a livelihood”
Socrates then said that just because exercise and training are not compulsory for a citizen one shouldn’t make this the excuse for being a whit less careful in attending to ones self. No activity in life will be hindered or hurt by keeping your body in the best possible shape.
“For in everything that we do the body is useful; and in all uses of the body it is of great importance to be in as high a state of physical fitness as possible”
Now some fool might say that this doesn’t apply when we don’t use our body. Socrates would reply;
“Why even in the process of thinking and not using our body, it is a matter of common knowledge that grave mistakes may often be traced to bad health. And because the body is in a bad condition loss of memory, depression and discontent often attack the mind so violently as to drive out whatever knowledge it contains”
Socrates said that whoever is in great shape is likely to experience the opposite of these negative effects. They will experience improved memory, less depression and a happier life. He says;
“Surely a person of sense would submit to anything, like exercise, so as to obtain a well functioning mind and a pleasant, happy life”
Socrates concludes by saying;
“It is a disgrace to grow old through sheer carelessness before seeing what manner of person you may become by developing your bodily strength and beauty to their highest limit”
Moralities and the Moral Republic 