Clay Christensen, a man I deeply respect, has the answer:
“Christensen had seen dozens of companies falter by going for immediate payoffs rather than long-term growth, and he saw people do the same thing,” writes Larissa MacFarquhar for the New Yorker. “In three hours at work, you could get something substantial accomplished, and if you failed to accomplish it you felt the pain right away. If you spent three hours at home with your family, it felt like you hadn’t done a thing, and if you skipped it nothing happened.
“So you spent more and more time at the office, on high-margin, quick-yield tasks, and you even believed that you were staying away from home for the sake of your family. Christensen had seen many people tell themselves that they could divide their lives into stages, spending the first part pushing forward their careers, and imagining that at some future point they would spend time with their families—only to find that by then their families were gone.”
In other words, you become what you prioritize. Metamorphosis from sustained work-a-holic into a well-rounded and interesting person doesn’t just happen.