Nothing depresses me more than reading about happiness. Why? Because there’s entirely too much advice out there about how to achieve it. As Frédéric Lenoir points out in Happiness: A Philosopher’s Guide (recently translated from its original French), great thinkers have been discussing this topic for more than 2,000 years. But opinions on it still differ. Just scan the 14,700 titles listed in the “happiness” subgenre of self-help books on Amazon, or watch the 55 TED talks tagged in the same category. What makes us happy? Health, money, social connection, purpose, “flow,” generosity, gratitude, inner peace, positive thinking… Research shows that any (or all?) of the above answers are correct. Social scientists tell us that even the simplest of tricks—counting our blessings, meditating for 10 minutes a day, forcing smiles—can push us into a happier state of mind.

A version of this article appeared in the July–August 2015 issue (pp.130–131) of Harvard Business Review.