Remember how it felt to be a kid on Christmas morning? We don’t often experience highs like that as adults. Oh, holidays are still pleasant, but they’re more work than they used to be. And any “high” is immediately followed by a “low” — something that was easier to take in stride as a child, when the next holiday or birthday party or field trip was always just around the corner.

I’m coming down from a “contact high”: That is, time spent with my friends and classmates at a recent reunion. I’m not going to lie (although I am going to use blatantly ‘80s slang): I had a blast. But now the afterglow is wearing off. It’s back to business as usual.

I used to wonder, as many people have, why human beings couldn’t be happy all the time. We seem to expect it. We are uncomfortable with sadness; we don’t like it. We speak of being “depressed.” Actually, of course, depression is a medical condition involving certain brain chemicals. Most of us aren’t really depressed, not medically anyway. We’re just sad.

I’ve come to a conclusion about happiness. I don’t think we’re supposed to be happy all the time, or even most of the time. I think it’s unfair to suggest that we should. The story of the Garden of Eden attempts to explain what I’m talking about — namely, that our free will comes with a price, and that price is unhappiness, at least from time to time.

Our choices make us unhappy. Our ability to choose the direction our lives will take makes us unhappy. Even choosing happiness can make us unhappy, as happiness can only be fleeting. We are built for contrasts: There can be no satiety without hunger, no dark without light, no unhappiness without happiness.

Like any living thing, happiness (laughter, sunshine, love) takes specific care. You have to work at it. Maintain ties with people who make you happy. Choose positivity in your day-to-day demeanor. Remember good times. But don’t expect to be happy all the time. Flowers need rain to grow, too. And happiness in this lifetime comes only in glimpses. We’re not ready to see Heaven…not yet.