In a speech called “A Way of Life,” which Sir William Osler, a famous Canadian physician, gave at Yale University more than 100 years ago, he explained a simple yet powerful technique he’d adopted: “living for the day only, and for the day’s work … in day-tight compartments.”

In his speech, Dr. Osler said that his “compartment” idea came to him while he was riding on an ocean liner. A warning light went off and all the watertight compartments suddenly slammed tight below the decks. Observing this, he had a revelation: By concentrating solely on one day’s work and shutting out all other thoughts and distractions, it would be possible to get a day’s work done without “mental distress” or “worries about the future.”

Draw a circle, Dr. Osler told his audience, around one 24-hour period of time. Determine what you can do in that time and make a decision not to bother your mind with worries about what you need to accomplish outside of that circle.

An example: A tourist was visiting a cathedral where an artisan was working on a huge mosaic. Seeing a vast empty wall looming before the artist, the tourist asked, “Aren’t you worried about all the space that you need to fill up and how you will ever finish it?”

The artist replied that he knew how much he could do each day. Each morning, he marked out the area of the wall he would complete and he didn’t let himself worry about what lay outside the space he’d marked. He just took one day at a time, knowing that one day he would be done.

A lot of the obstacles we face in our writing are like that Great Wall. We can worry about the bigger picture and fritter away our energies. Or we can simply draw a circle around the day and focus totally on completing the work at hand. Write on!