I go swimming to try to forget that I'm dying. But then I remember that nobody lives forever.

I spend most evenings at the same pool in which my kids and I swam when they were little. Now I wonder how many laps I have in me.

For me getting old happened suddenly — or maybe I was too busy working and raising children and trying to make a dent in what I thought was my life's larger mission to pay attention to it. Rachel Levit Ruiz / for NBC News
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At the local pool, where I come almost every evening from 5:30 to 6, I am the old lady in the lap lane. I am not the crabby old lady in the lap lane, which is good: I smile and say hello and goodbye to the lifeguards before and after my laps no matter how undeservedly brusque I think they are with me. I hope with every little cheery wave I offer that, in the case of an emergency, it will be the reason they jump in right away to save me and not pause and think to themselves, Ugh, not her.

I swim in the same pool where I took my three children when they were young and never seemed to get tired; now I wonder how many laps I have left in me.

My father died at 66 — five years older than I am now — taking his last breath at the hospital once my mother went home to shower, following days and weeks at his bedside in a vigil. Sparing her was his final act of kindness, after a lifetime defined by unbroken gestures of kindness.

I dive in the deep end and abandon the ever-racing thoughts of all my daily business. I cannot, however, successfully annihilate the notion of dying that lately pops up more frequently, especially on the anniversary of my breast cancer diagnosis — stage 1 — which was followed by a lumpectomy, brachytherapy and years of follow up medications. (The anniversary is October, as if I need the reminder.)

Kelly Clarkson is singing on the loudspeaker, echoing around the walls of the building. This song is old by the standards of the young lifeguards here — 2009. I know because I sang it a lot in the car while driving my three sons to practices and wrestling meets: “Because of you, I find it hard to trust not only me, but everyone around me. Because of you, I am afraid.”

My mother lived to be 80. Her last three years were mostly spent in bed at home and then in hospitals; the final months she had a breathing tube and her last hours were belabored — suffering, gasping.

For me getting old happened suddenly — or maybe I was too busy working and raising children and trying to make a dent in what I thought was my life's larger mission to pay attention to it. No gradual hinting, no inch-by-inch increments, no sliding down the hill once I was over it; old age for me arrived with a slam ... or maybe with the quiet flipping open of a chart, 12 years ago this month, in an oncologist's office.

While I swim, there is a gentleman who arrives at our pool in a rolling walker — the kind with a seat — pushing ahead, his back hunched. At a lounge chair, he deposits his bag on a nearby chair (I imagine it contains a towel and his car keys) and pushes the walker close to the side of the pool. He grabs onto the stairs and, with what looks like great trouble and discomfort, angles his body into the water. He swims laps smoothly in a lane near mine; I realize it is perhaps the only time of day when his body complies with his mind's instructions.

My grandmother, when she was alive, used to call the obituaries the "Irish comics," and I thought that was odd because they weren’t then and even now aren’t funny. But now I, too, read them most days. I used to glance at the obits for the parents of friends and, through tears, I have read them for the sons and daughters of loved ones. Now it is my friends, and friends of friends, who are featured — neighbors, co-workers. All of it, for some reason, feels like a shock.

The loudspeakers start booming a song from Adele's first album; I know every song on that CD by heart, because I used to sing to it on the long drive to work. “When did this Adele song come out?” yells the high school-ish boy sitting in the lifeguard's chair to the young woman resting above the lap lanes.

“2010,” she shouts back.

“2008 or 2009,” he corrects her, in a voice louder than his whistle. “Wow, that is old.”

The song is not old to me; I am old to me.

I used to occupy the office of an adjunct at the university who was found dead in her apartment after she did not show up to teach a class. The desk drawers I inherited from her were filled with packages of ketchup and paperclips. “I feel creepy being in her office,” I told David.

“We’re all in offices of dead people,” he said. And he was right.

There’s a mother-son duo who are here most early evenings when I am, both lean and with the same length of curly brown hair — his in a ponytail. He appears to be in his 30s, which is about the age of my oldest son. She seems to be my age and as she sits on the side of the pool in her bikini, calling him “dear”; her stomach has thin, crisp folds like a manila envelope.

Swimming is the only time I ever feel unburdened by responsibilities, relationships, deadlines, duties. It grants me pause from the running accounting and inventory of what I have done, what I have not done and, most pressingly, what I have yet to do.