It´s called step by step, by Michael Ende.
An old road sweeper tells his friend. “It´s like this. Sometimes, when you´ve a very long street ahead of you, you think how terribly long it is and feel sure you´ll never get it swept. And then you start to hurry. You work faster and faster and every time you look up there seems to be just as much left to sweep as before, and you try even harder, and you panic, and in the end you´re out of breath and have to stop—and still the street stretches away in front of you. That´s not the way to do it.
You must never think of the whole street at once, understand? You must only concentrate on the next step, the next breath, the next stroke of the broom, and the next, and the next. Nothing else.
That way you enjoy your work, which is important, because then you make a good job of it. And that´s how it ought to be.
And all at once, before you know it, you find you´ve swept the whole street clean, bit by bit. What´s more, you aren´t out of breath. That´s important too…”
So don´t always live in the future, but in the past. Don´t always look at the big things that will come, but concentrate on the little things that will lead you to the big goal. Be careful not to exhaust on your way to the aim.