I have felt this, for instance, training at a tennis academy in Florida, immersed in the sort of regimen designed for 12- and 13-year-olds dreaming of scholarships to Division I schools — on the court four, five hours a day in the heat and closeness, running back and forth along the baseline, catching and heaving a medicine ball tossed by a coach. I’ve hit groundstrokes against the wall at my club in midwinter, attended tennis-specific plyometrics and TRX workouts, been beaten down by all manner of younger, better players in league play and at tournaments.

But I improved as a result of all of it — and I am still improving. I have a much better backhand volley than I did this time last year. Is it really good or even that good? Am I that good? No! I am 63. And I am not really concerned about where all this winds up. It’s the getting there I’m enthralled with.

THERE are quantifiable benefits often associated with taking up something like tennis and getting better at it. Your brain, it’s thought, will be recast and strengthened. Denise Park, a neuroscientist at the University of Texas at Dallas, randomly assigned more than 200 older people to different new activities for roughly 15 hours a week and found that only those who had learned and refined a complicated skill improved their memories. Other researchers say the intense and prolonged physical exertion of a game like tennis may fend off cancer by slowing the decline of your telomeres, the tiny caps on the ends of your DNA strands that tend to shorten and fray with age, and leave the DNA subject to greater risk of mutation during cell division and replication. You will, I am convinced, do good things for your heart: Senior Olympians have been found, on average, to have a cardiovascular “fitness” age 20 years less than their chronological age.

But let’s not get carried away. As the doctor and writer Jerome Groopman noted recently, “the genesis of aging is still a mystery.” There may be many aspects to why it occurs, and at what rate it occurs. There may be ways of increasing longevity, and for any one of us they may work, or not. If you are taking up tennis, or something like tennis, and committing to getting better at it to add years to your life, I wish you all the luck in the world. Just don’t bet on it.

I can promise you that you will come to know yourself better. Isn’t that what Montaigne said we were supposed to do later in life? I have learned, over these past seven or eight years, that I can deal with being humbled (but not humiliated); that my energy level is highest late in the afternoon; that I am more impatient even than I knew; that my left stride is longer than my right (which can aggravate balance problems); that I am harder on myself than on my opponents or doubles partners; that my hand-eye coordination is better when my right eye is doing the focusing; that I am a pretty good loser; and that I like being among others who love playing tennis — worrying their games, talking about the sport, searching for how to change this or that stroke or strategy in the tiniest way to make it more effective — as much as I have come to love playing tennis itself.

To learn most of these things, through struggling to improve, you will need the personal attention of a coach. You may have heard of the psychologist K. Anders Ericsson and the “10,000 hours of practice” rule. It is often misconstrued a bit: The key is typically not the time you put in to get better, but the time you spend under the watchful eye of a coach, teacher or trainer — someone who can spot quickly what you are doing wrong and immediately correct it, or try to. I won’t live long enough to have 10,000 hours to devote to personalized tennis training, but I have spent lots of time with a coach. There can be no improvement — not the kind I’m talking about — without that coaching.