The doctor prescribed walking — I've filled it for ten years

Ten years ago the doctor did not write medicine on my prescription pad. She wrote one line: brisk walking, forty minutes a day, five times a week.

I was thirty-eight. My checkup report was a wall of red: blood pressure, blood lipids, fatty liver — three items over the line. I stared at the line on the pad. She said, "Don't underestimate walking. It is the cheapest exercise in the world, and the one people give up on least. What matters is that you come every day."

In the first week I wanted to quit. Forty minutes of brisk walking, for a man who got winded climbing three floors, was endless. What kept me going was something else she said: "Don't treat it as exercise. Treat it as forty minutes of official business every day — business you have with yourself. Rain or shine. The kind where you lose pay if you take leave." So I set my own penalty. Every day I broke the chain, ten yuan went into a jar, and at the end of the month I donated the money.

The first year, the body changed first. After three months my blood pressure came down. After six, the fatty liver went from severe to mild. After a year the report was all green. The doctor looked at the two reports side by side and said, "You have just saved yourself a surgery."

The second year, the mind changed. Those forty minutes turned out to be the only solitude in my day. No calls, no audiobook in my ears, just walking. Problems from work often untied themselves halfway along the route. Things I had swallowed went into the river and came out digested. My wife said my temper was better when I came back from a walk. I told her, "Those forty minutes are me walking myself back into shape."

By the fifth year, walking had grown beyond official business. On my fixed route I met a group of fellow prescribers — also sent out by doctors, also years into it. We became an informal prescription walking club. Twice a year we do a long brisk walk together; the rest of the time we check in on a group chat. The oldest is Sister Zhou, seventy-four. Her prescription is for bone density. She said something we still quote: "This medicine has no side effects. Its only contraindication is laziness."

A prescription for exercise lasts ten years not because of iron will, but because the question "am I walking today" was settled ten years in advance.

Ten years, more than four thousand days. I have filled five notebooks with walking records: kilometers, steps, which days it rained and I moved indoors, which days I was traveling and paced the hotel corridor end to end. Reading them moves me more than reading the checkup reports. Not one page says "didn't feel like walking today." Many say "very tired today, walked twenty minutes, still counts." The doctor was right: the great virtue of this prescription is that it allows a discount but never an absence.

At last year's checkup she read my results and renewed the prescription for another ten years. She said, "In twenty years of practice, the only prescription I have written that keeps patients away for a decade is walking."

I am sixty now. The forty minutes happen every day without discussion. The route has spread from the compound to the river, the park, the old town — ten years of measuring this city with my feet. I call it the dividend I wrote for myself: the body pays the principal, time pays the interest.