As I was listening, I realized that we live in a culture that makes happiness our ultimate goal. I realized that I had been feeling shame, worry, and a sense of failure during those stretches of the day when I wasn't feeling happy. David says a more meaningful question to ask than "Am I happy?" is "Am I living a life of value?" and "Am I living in accord with my values?" Our emotions (pleasing or challenging) give us valuable information - and point us toward what we value. When we live lives of meaning in accord with our values, happiness is a side effect.
Today, instead of checking in to see if I'm happy, I'll check in to see if I'm making choices in line with my values. I'll remember that valuable work is sometimes difficult. I won't be afraid of that difficulty.