Jane Brody on health and aging.

I was going to skip my daily swim the other morning. I had already walked three miles with a friend and taken my dog to the park for his exercise. I was really tired, my back was sore, I had a column to write and lots to do around the house.

But I knew from past experience that I would feel much better after 40 minutes of swimming laps. So in I went. And, yes, I did feel better — not just refreshed, but more energetic, clearheaded and better prepared than I would have been otherwise to tackle the day’s essentials.

Michelle Segar, who directs the Sport, Health and Activity Research and Policy Center at the University of Michigan, would say I had reframed my exercise experience, making it ever more likely that I would continue to swim — even on days when I didn’t feel like doing it — because I viewed it as a positive, restorative activity. Indeed, exercise is something I do, not because I have to or was told to, but because I know it makes me feel better.

Dr. Segar, a psychologist who specializes in helping people adopt and maintain regular exercise habits, is the author of “No Sweat: How the Simple Science of Motivation Can Bring You a Lifetime of Fitness.” Her research has shown that even people who say they hate to exercise or have repeatedly fallen off the exercise wagon can learn to enjoy it and stick with it.

Three years ago, I wrote about research by Dr. Segar and othersshowing that promoting physical activity to prevent or control disease, lose weight or sculpt one’s body, and prescribing doses as if exercise were medicine, wouldn’t get most people to do it and keep doing it.

“Health is not an optimal way to make physical activity relevant and compelling enough for most people to prioritize in their hectic lives,” Dr. Segar said in an interview.

Though it seems counterintuitive, studies have shown that people whose goals are weight loss and better health tend to spend the least amount of time exercising. That is true even for older adults, a study of 335 men and women ages 60 to 95 showed.

Rather, immediate rewards that enhance daily life — more energy, a better mood, less stress and more opportunity to connect with friends and family — offer far more motivation, Dr. Segar and others have found.

“I like to think of physical activity as a way to revitalize and renew ourselves, as fuel to better enjoy and succeed at what matters most,” she said.

In her new book, she describes strategies to get even the most sedentary people off their duffs, starting with ways to overcome past failures and negative feelings about exercise that make it feel more like punishment than pleasure.

Instead of the recommended half hour a day or 10-minute doses of moderate exercise three times a day on most days, Dr. Segar suggests focusing on the idea that “everything counts” — taking the stairs instead of the elevator, weeding the garden, dancing, even walking to the water cooler.

“We should count any and every opportunity to move that exists in the space of our lives as valid movement worth doing,” she wrote. She advocates adopting a food marketer’s approach to workouts: Enjoy “snacks” of exercise that can entice gradual increases in how much is “consumed.” And like the calories in food snacks, it all adds up.

Dr. Segar likens the choices to Baskin-Robbins’s 31 flavors: “There are so many options — ‘What do I feel like doing today?’ — then picking the ‘flavor’ of physical activity that feels right for that day and moment.” The neuroscience of reward has shown that this approach can foster and reinforce positive feelings about being active.

Also important is giving oneself permission to make self-care through physical activity a priority. Dr. Segar wrote: “When we do not prioritize our own self-care because we are busy serving others, our energy is not replenished. Instead, we are exhausted, and our ability to be there for anyone or anything else is compromised.”

People who make physical activity a priority don’t necessarily have more time than others. Rather, they make sure to schedule time for it because they know it enhances their performance and the quality of their daily lives. It has been shown, for example, that schoolchildren who are given exercise breaks are better able to to pay attention and learn.

Citing a “paradox of self-care,” Dr. Segar wrote, “The more energy you give to caring for yourself, the more energy you have for everything else.” She suggests viewing physical activity as a power source for everything else you want to accomplish. “What sustains us, we sustain,” she wrote.

To those who feel they are neglecting family to fit in exercise, she suggests taking them along. The routine can help foster a culture of physical activity at an early age. When my brother and I were young, my father took us on his weekend walks. He taught us to swim as preschoolers and launched a lifetime of enjoyment in the water. Now in our 70s, both of us continue to appreciate what physical activity brings to everything else in our lives. We feel like slugs when we can’t exercise.

Even those with the best intentions often set themselves up for failure by establishing rigid exercise goals. They try to do too much, and when they can’t keep it up they give up and chalk it up as another exercise failure. In place of a performance goal, Dr. Segar suggests setting a “learning goal” — learning to be flexible and cutting yourself some slack when needed.

Consistency trumps quantity when trying to establish a lifetime of fitness. When a last-minute task cuts into a planned workout, you should not skip the session altogether. Even 10 or 20 minutes of activity is better than none.

It also helps to anticipate challenges to your exercise routine, using an “if-then” exercise tool. If, for example, you are too tired after work to go to the gym, think about a replacement activity you might enjoy, like taking a sunset walk alone or with a partner, friend, child, dog or even a neighbor’s dog.

Or, in the future, go to sleep and get up a half hour earlier to fit in physical activity before life’s demands get in the way.