Researchers from the Max Planck Institute for Evolutionary Biology in Germany recruited some tough subjects for their study on compassion: a group of 2-year-olds. For their experiment, adults dropped something and then pretended to have trouble picking it up, at which point the toddlers were either allowed to help, or watched someone else help.  More from Prevention: 4 Stories Of Ultimate Acts Of Altruism   The results? The toddlers’ pupils dilated equally in both situations, indicating that they got a positive boost in both situations. Basically, the kids wanted the other person to get help, and got satisfaction even just by seeing it happen. But when we get older—as anyone beyond the preschool set can attest—doing good isn’t always so simple as we get older. Thanks to a buildup of not-so-happy life experiences, it’s easy to lose touch with our sense of altruism, says Susan Bartell, PsyD, a New York-based psychologist. “Or we want to help, but the desire to do so gets buried deep down beneath all of our worries, obligations, and busy schedules,” she says.  Before you start picturing your heart shriveling to the size of the Grinch’s, consider this: By actively behaving with kindness, you just might build your compassion back up to toddler-size proportions, says Bartell. It could mean doing more volunteer work, letting a mom with a baby cut ahead of you in line, or even just being extra patient with your partner when he’s stressed from a hectic day at work. “The more you behave kindly, the more you see how good it makes you feel,” Bartell says.   Need some suggestions? Check out 13 Simple Ways To Be Nicer.