You prepared well and aced your presentation at work, or passed your exam with flying colors. But your health might be a little worse for wear, and not just because of the late nights you pulled. It might be the not-so-tiny difference between whether you worked hard because you expected to do well, or you worked hard because you didn’t want to do poorly.

People who are optimistic generally have better health outcomes than others, many studies have found. But just how positive thoughts translate to better health is still a mystery.

Many optimism studies have looked at traumatic or extreme events such as receiving a severe cancer diagnosis. Now a few hundred college students have stepped up to help provide clues about optimism’s role in day-to-day life. During the school term they reported how much their work was driven by the desire to achieve positive results or to avoid negative ones, and during finals week they reported on their mental and physical symptoms.

The more optimistic among the more than 300 students ended the term with higher marks for their health, according to findings published in the Journal of Happiness Studies.

To reap health benefits of optimism, it wasn’t enough just to think positively, however. What was the practical difference in how the students approached their studies? Optimists set daily goals that focused on achieving positive outcomes, then directed their attention and efforts toward those outcomes. In so doing, their cognitive and emotional resources were not consumed by negativity.

Those students can teach us a thing or two: Focus on what you stand to gain rather than what you have to lose. Get started on your “To do” list and ditch the “Don’t do” lineup.