I tell you, because military training is not publicly…

““I tell you, because military training is not publicly recognised by the state, you must not make that an excuse for being a whit less careful in attending to it yourself. For you may rest assured that there is no kind of struggle, apart from war, and no undertaking in which you will be worse off by keeping your body in better fettle. "For in everything that men 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 efficiency as possible. Why, even in the process of thinking, in which the use of the body seems to be reduced to a minimum, it is 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, discontent, insanity often assail the mind so violently as to drive whatever knowledge it contains clean out of it. But a sound and healthy body is a strong protection to a man, and at least there is no danger then of such a calamity happening to him through physical weakness: on the contrary, it is likely that his sound condition will serve to produce effects the opposite of those that arise from bad condition. And surely a man of sense would submit to anything to obtain the effects that are the opposite of those mentioned in my list. "Besides, it is a disgrace to grow old through sheer carelessness before seeing what manner of man you may become by developing your bodily strength and beauty to their highest limit. But you cannot see that, if you are careless; for it will not come of its own accord.””

— Xenophon Memorabilia. 371BC Marchant translation