They always say the last five to 10 pounds are the toughest. When a person starts working towards a goal, such as losing 20 pounds or running a 10K race, it can seem easy in the beginning — we are inspired and motivated and our progress is often easy to see. Unfortunately, staying focused on a goal, especially after the halfway mark, is more difficult.

Why does motivation seem to fizzle out as we get closer to our goal? Canadian researchers have found a possible explanation: As we begin working towards a goal, motivation is characterized by our focus on positive things we can do, Olya Bullard, one of the authors, told TheDoctor. For example, if we are trying to lose weight, we focus on eating fruits and vegetables, smaller portions and exercising.

Unfortunately, staying focused on a goal, especially after the halfway mark, is more difficult.

Motivation is not always the same thing, though we tend to think of it that way. It is a process that changes with our progress. At the start of an endeavor — losing weight, jogging — the only way to go is up. The researchers called this “promotion motivation.”

But in the later stages of pursuing a goal, outward progress can slow, and we must stay motivated even when we face setbacks or the need to extend our run . So our motivation becomes characterized by what we can do to avoid or obstacles we need to overcome to reach our goal — something the researchers called “prevention motivation.” For example, when trying to lose weight, in addition to the fruits and vegetables we have been eating, we have to also be persistent and avoid slipping up. You need to avoid eating out or telling yourself you deserve a piece of cake.

The researchers conducted five experiments. In several, participants simply imagined working towards a goal. In the others, participants were given an actual goal to work toward. As the researchers predicted, participants were more interested in advancing as they started working towards their goal and more interested in preventing slip-ups as they neared their goal.

“We switch our reference point about halfway to our goal,” said Bullard, an assistant professor at the University of Winnipeg. As we begin to work towards a goal, we use our starting point as a reference. We might think, “I lost five pounds!” Our accomplishments represent something positive.

As we get closer to our goal, we start to think about the work we still have to do, said Bullard. So we think, “I have five pounds to go.” Our focus is on the work we have not done. “The strategies you choose to keep yourself motivated should change depending on how close you are to reaching your goal,” adds Bullard. Those who are just starting should focus on strategies that provide positive reinforcement, or some reward. If you are trying to lose weight, for example, buy something for yourself, just not sweets!

For people in later stages of pursuit of a goal, what not to do becomes more motivating. Bullard suggests you ask yourself what you can avoid — such as, “What can I cut out of my diet?” You might also focus on negative things you will avoid by reaching your goal, such as “I will not feel embarrassed in a bathing suit.” This can serve as a new goal that refreshes your commitment.

The study is published in the Journal of Consumer Psychology.