"A lot of people, especially young adults, are trying to figure out 'where do I invest my time?'" Dr. Waldinger says. "So you can spend your whole time -- nights and weekends -- working to advance your career, and that would probably advance your career. But it might really screw up your life."
Although there's no official standard for where personal relationships rank compared to diet, exercise, sleep, and all those other common-sense health habits, they require just as much of an investment, if not more, to reap the rewards.
"It doesn't mean that one [healthy habit] replaces the other, but they all kind of work together," he emphasizes. "So rather than figuring out which one is more important, it's figuring out what's a really good combination. And maybe a combination where the sum of the parts is bigger than the individual parts."