I recently turned forty years old. Apparently this is a Big Deal and I’m supposed to have a lot of feelings about it.

I am not having a ton of feelings. Forty feels about right. When I was a kid I had trouble even picturing myself as a teenager and I interpreted this as proof that I would die before reaching that stage. This inability to see the future has persisted–to my ongoing disappointment–and I continue to be surprised at every birthday.

Every birthday brings with it a poignant new math problem. You see my college friend Katie died in 2004 when we were both twenty years old. It was sudden and shocking and happened over the summer. Later that year I turned twenty-one, but she did not. After that I turned twenty-two, but she did not.

You see where this is going. My fortieth birthday marks a doubling of Katie’s time here, and when I picture my forty years I don’t see four sets of ten. I see two sets of twenty.

I have another college friend who turned forty this year who is currently on hospice care as he winds down a multi-year battle with cancer. He has lived double what Katie lived, but his life won’t extend much further.

He knows he won’t ever turn forty-one, but the rest of us have no fucking clue what’s in store for us. Maybe I die at forty too. Or fifty. Maybe I’ll hit eighty and double his lifespan and quadruple Katie’s. God, that would be something.

Not a single moment is guaranteed to us, so I am pretty pleased to have made it to forty.