"Are you happy?" I asked my brother, Ian, one day.
"Yes. No. It depends on what you mean," he said.
"Then tell me," I said, "when was the last time you think you were happy?"
"April 1967," he said.
It served me right for putting a serious question to someone who has joked his way through life. But Ian's answer reminded me that when we think about happiness, we usually think of something extraordinary, a pinnacle of sheer delight. And those pinnacles seem to get rarer the older we get.
For a child, happiness has a magical quality. I remember making hide-outs in newly cut hay, playing cops and robbers in the woods, getting a speaking part in the school play. Of course, kids also experience lows, but their delight at such peaks of pleasure as winning a race or getting a new bike is unreserved.
In the teenage years, the concept of happiness changes. Suddenly it's conditional on such things as excitement, love, popularity and whether that zit will clear up before a prom night. I can still feel the agony of not being invited to a party that almost everyone else was going to. But I also recall the ecstasy of being plucked from obscurity at another event to dance with a John Travolta look-alike.
In adulthood the things that bring profound joy - birth, love, marriage - also bring responsibility and the risk of loss. Love may not last, loved ones die. For adults, happiness is complicated.
My dictionary defines happy as "lucky" or "fortunate", but I think a better definition of happiness is "the capacity for enjoyment". The more we can enjoy what we have, the happier we are. It's easy to overlook the pleasure we get from loving and being loved, the company of friends, the freedom to live where we please, even good health.
I added up my little moments of pleasure yesterday. First there was sheer bliss when I shut the last lunchbox and had the house to myself. Then I spent an uninterrupted morning writing, which I love. When the kids came home, I enjoyed their noise after the quiet of the day.
You never know where happiness will turn up next. When I asked friends what makes them happy, some mentioned seemingly insignificant moments. "I hate shopping," one friend said. "But there's this clerk who always chats and really cheers me up."
Another friend loves the telephone. "Every time it rings, I know someone is thinking about me."
We all experience moments like these. Too few of us register them as happiness.
While happiness may be more complex for us, the solution is the same as ever. Happiness isn't about what happens to us; it's about how we perceive what happens to us. It's the knack of finding a positive for every negative, and viewing a set-back as a challenge. It's not wishing for what we don't have, but enjoying what we do possess.