That's the work / productivity philosophy of Cal Newport. He targets it to students but all should consider it:
Maintain a small number of things that you return to, and do hard work on, again and again, over a long period of time. Choose things that actually interest you, but don’t obsesses over choosing the perfect things — as perfect goals, like perfect majors, probably don’t exist. Keep this hard work quarantined to a reasonable number of focused hours each day, and harness the rest of the time to recharge, relax, and, in general, enjoy life. Or, to put it in a more familiar wording: Do Less. Do Better. Know Why.