"And without the power to concentrate -- that is to say, without the power to dictate to the brain its task and to ensure obedience -- true life is impossible. Mind control is the first element of a full existence.
"Hence, it seems to me, the first business of the day should be to put the mind through its paces. You look after your body, inside and out; you run grave danger in hacking hairs off your skin; you employ a whole army of individuals, from the milkman to the pig-killer, to enable you to bribe your stomach into decent behaviour. Why not devote a little attention to the far more delicate machinery of the mind, especially as you will require no extraneous aid? It is for this portion of the art and craft of living that I have reserved the time from the moment of quitting your door to the moment of arriving at your office.
"'What? I am to cultivate my mind in the street, on the platform, in the train, and in the crowded street again?' Precisely. Nothing simpler! No tools required! Not even a book. Nevertheless, the affair is not easy.
"When you leave your house, concentrate your mind on a subject (no matter what, to begin with). You will not have gone ten yards before your mind has skipped away under your very eyes and is larking round the corner with another subject.
"Bring it back by the scruff of the neck. Ere you have reached the station you will have brought it back about forty times. Do not despair. Continue. Keep it up. You will succeed. You cannot by any chance fail if you persevere."
Bennett, A. (1959). Controlling the Mind. In How to live on 24 hours a day (pp. 54-56). Kingswood, Surrey: World's Work.