The old expression-money can’t buy happiness—may be true. But so is the reverse—that happiness may be able to bring in money.

A new study has found that the happier and more satisfied we are in our teens and early 20’s, the more money we’ll make years down the road.

Researchers used data from more than 10,000 Americans tracking their emotional well-being at ages 16 and 18, and their life satisfaction at age 22. Positive emotions and happiness were correlated significantly with income at about age 29. However, having had an unhappy adolescence predicted income in adulthood that was about 30% less than average.

According to the study, happiness was associated with several factors that could influence future income, including increased likelihood of getting a college degree and then getting hired, heightened optimism, and being extraverted and less neurotic.

Interestingly, another study found that unhappy 8-10-year olds are more likely to become materialistic than happier kids the same age—especially if they watch a lot of TV, where the message that money and possessions lead to happiness is reinforced over and over and over.