In addition to being happier, men with kids work a lot more than childless men, even though their time tends to be constrained by family life. According to the 2001 study, men living with their children worked, on average, 6.6 hours more each week than childless men, and two hours more than men who were not living with their kids. Yet the impact on free time doesn’t seem to bother most dads; on the contrary, according to a 2016 Boston College study, Millennial fathers are significantly more likely than nonfathers to say, “My life conditions are excellent.” One plausible explanation for these data patterns is that happy, hard-working men are the ones most likely to become fathers. But I believe an equally likely explanation is that hard work that provides for those we love brings happiness. This is consistent with a body of evidence on what psychologists call the “helper’s high,” which refers to the good feeling we get when we sacrifice for others. In one study in the journal Nature Communications, researchers showed that participants in a giving experiment felt significantly happier when they behaved charitably. Sacrificing for others—especially those you love most—is like a natural happiness drug. This would explain the paradox I saw in my father. Obviously, the helper’s high can be overwhelmed when people take on more than they can bear. Plenty of literature shows the difficulties that family members face when caring for loved ones with intensive needs, or when experiencing severe financial duress. But under ordinary circumstances, when we leave our comfort zones of self-care and seek to serve others instead, we can find greater happiness.