We all sorely complain of the shortness of time, and yet have much more than we know what to do with. Our lives are either spent in doing nothing at all, or in doing nothing to the purpose, or in doing nothing that we ought to do. We are always complaining that our days are few, and acting as though there would be no end of them.Being quite popular in his day, he was an imperial advisor to both emperors Caligula and Nero. But he didn't choose to advise the best of leaders (did he actually have a choice?); after allegedly conspiring to kill Nero (which he didn't), Nero ordered him to commit suicide (which he did). Apparently there was no connection between Seneca and the failed plot.
Anyhow, the year before he died he wrote out all this advice to a solider named Lucilius bundled together under the title Epistulae morales ad Lucilius, but really they were intended for anyone who read them. This passage is his advice on how to keep fit both body and mind. Perhaps his ideas are a little outdated (he lived 2000 years ago). Does any of this look familiar? (not a rhetorical question) I copied the passage from here, Epistle 15. Fair warning, he trails off a little towards the end.
The old Romans had a custom which survived even into my lifetime. They would add to the opening words of a letter: "If you are well, it is well; I also am well." Persons like ourselves would do well to say. "If you are studying philosophy, it is well." For this is just what "being well" means. Without philosophy the mind is sickly, and the body, too, though it may be very powerful, is strong only as that of a madman or a lunatic is strong. This, then, is the sort of health you should primarily cultivate; the other kind of health comes second, and will involve little effort, if you wish to be well physically. It is indeed foolish, my dear Lucilius, and very unsuitable for a cultivated man, to work hard over developing the muscles and broadening the shoulders and strengthening the lungs. For although your heavy feeding produce good results and your sinews grow solid, you can never be a match, either in strength or in weight, for a first-class bull. Besides, by overloading the body with food you strangle the soul and render it less active. Accordingly, limit the flesh as much as possible, and allow free play to the spirit. Many inconveniences beset those who devote themselves to such pursuits. In the first place, they have their exercises, at which they must work and waste their life-force and render it less fit to bear a strain or the severer studies. Second, their keen edge is dulled by heavy eating. Besides, they must take orders from slaves of the vilest stamp, - men who alternate between the oil-flask and the flagon [a prize-fighting ring], whose day passes satisfactorily if they have got up a good perspiration and quaffed, to make good what they have lost in sweat, huge draughts of liquor which will sink deeper because of their fasting. Drinking and sweating, - it's the life of a dyspeptic!
Later he concludesNow there are short and simple exercises which tire the body rapidly, and so save our time; and time is something of which we ought to keep strict account. These exercises are running, brandishing weights, and jumping, - high-jumping or broad-jumping, or the kind which I may call, "the Priest's dance," or, in slighting terms, "the clothes-cleaner's jump." Select for practice any one of these, and you will find it plain and easy. But whatever you do, come back soon from body to mind. The mind must be exercised both day and night, for it is nourished by moderate labour. and this form of exercise need not be hampered by cold or hot weather, or even by old age. Cultivate that good which improves with the years. Of course I do not command you to be always bending over your books and your writing materials; the mind must have a change, - but a change of such a kind that it is not unnerved, but merely unbent. Riding in a litter shakes up the body, and does not interfere with study: one may read, dictate, converse, or listen to another; nor does walking prevent any of these things.
As to what the future's uncertain lot has in store, why should I demand of Fortune that she give rather than demand of myself that I should not crave? And why should l crave? Shall I heap up my winnings, and forget that man's lot is unsubstantial? For what end should I toil? Lo, to-day is the last; if not, it is near the last. Farewell.