America has a time problem. About half of us tell pollsters that we don’t have enough time to do what we want. Another survey found that most people would rather have two more weeks of vacation than two more weeks of pay. And every new “labor-saving’’ technology -- email, smart phones -- seems to make things worse, not better. Books for the time starved and productivity challenged would fill a small library. Beyond the books, there are the seminars, videos, apps, and “methods’’ (like “Getting Things Done’’) -- which feature books, videos, seminars and apps. Yet for all the advice that has been offered, I seriously doubt anyone has come up with the bit of wisdom on offer from a professor at Harvard Business School: Spend more time doing things for other people.