However, the evidence suggests that money only accounts for about 2 percent of the variance in happiness between people. If those pursuits don’t move the needle nearly as much as we’d expect, then where does happiness actually come from? For example, the longest-running study of human happiness (spanning across three generations and 80 years), the Harvard Longitudinal Study, found that high-quality relationships were the single most important factor for happiness throughout the lifespan. The quality of our relationships predicts happiness better than anything else studied. But when taking care of your happiness, don’t forget about social connection and altruism as important parts of your self-care routine.