Do you keep a journal or a diary? A daily reminder of how you have spent the past 24 hours? Your activities? Your thoughts? Your meals?

I have never been a diarist—I lack the patience to capture life with a daily entry. While my blog posts sometimes read like a page from a diary, they are too sporadic and their focus is too variable to be a realistic depiction of my daily life.

But there is one journal I am meticulous about. For the last 35 years, I have been logging my physical fitness workouts. It’s all there, in three spiral-bound steno notebooks. Every mile I have run, every stride on the elliptical, every Tabata-lite class I have taken, and every session with a trainer is listed in precise chronological order.

The series of places I have worked out at all make their appearance. The Cardiac Rehab Center at Holy Family Hospital, the microscopic fitness centers near my former Westchester laboratory, and park district facilities in Buffalo Grove and Deerfield are all included in my tiny block lettering. Each mention reminds me of a different phase in my life.

I record my weight and my maximum heart rate. Did I listen to a CD on a 5-mile voyage through the neighborhood? That’s listed too. (In this age of streaming I have stopped keeping track of my workout soundtrack.)

Over time snippets of other data have crept into the rows of statistics. A brief mention of a sore back explains a two-week absence of exercise. Acknowledgments of trips abroad, trips at sea, and trips through the USA all explain some of the gaps, as do references to the occasional medical procedures.

I can look through my logbooks and see how often I worked out on the days before our son or daughter were married—and how exhaustion kept me on the sidelines for a few days after. I can even see how the death of my mother affected my stamina and vigor in the weeks following her passing.

Of course, it is an incomplete picture of my last 35 years. There are no happy emojis at the birth of a grandchild and no sad ones at the loss of a pet. But examining each page does bring back memories—recollections of weddings, funerals, and travels.

Having those logbooks motivates me to keep on going, to keep on listing row after row of entries. And maybe I’ll include some notes to my future self—at least a smiling emoji or a thumbs up now and then!