Question: If you were running a 26-mile marathon and you were running out of gas or starting to feel everything (not in a good way), are you more likely to keep going if you have two miles left or ten?

Here, the difference may lie not in the physiology of your muscles and how good your sneakers are, but in the psychology of numbers. Research shows that once we perceive a goal to be within reach, the more likely we are to persist. As described in one study:

The closer people are to the goal, the more resources they invest in reaching it.

Research shows people have more motivation when proximity to a goal is framed as a smaller number. For example, it may seem obvious that telling someone 20 percent of a task is complete is better than saying 80 percent of the task is left, but it is also a better motivator to say that there is 20 percent left rather than 80 percent left. This phenomenon is known as the Law of Small Numbers. As Paul Dolan writes in Happiness by Design:

The law of small numbers makes your commitment to progress more salient.

How we monitor our progress toward completing a goal directly influences motivation. This has implications for the real world. Explicit feedback on goal progress can make a difference in education, in the workplace, in marketing, and more. As the authors suggest:

Weight-loss programs should design their goal-progress feedback system to highlight small distances. Specifically, these programs should consider customers’ levels of progress and emphasize whichever is smaller: the weight people have already lost or how much they need to still lose…

Financial services could benefit from this too. They can develop programs or financial products that encourage consumer saving by providing feedback that emphasizes small areas of goal progress—either what has been saved to date or what remains to meet the goal.

Along similar lines, telling a student they have completed 20 percent of a book is more motivating than saying they have 80 percent more to read.

The good news is you have less than 1 percent of this article left to go!