Consider the wall squat, for instance, says Dr. James Gladstone, the chief of sports medicine at Mount Sinai Health Center in New York City. This exercise requires little expertise or equipment, apart from a wall, but robustly improves leg strength. Simply stand upright a foot or so from a wall, legs shoulder distance apart. Press your back against the wall and slide down until your thighs are almost parallel with the ground. (Stop earlier if your knees hurt.) Hold this simulated sit as long as you can. “If that means five seconds, fine,” Dr. Gladstone says. Slide back up the wall, rest a few seconds, and slide down to sit again.

For upper-body strengthening, raid the pantry, suggests Jennifer Copeland, a professor and director of the Active Healthy Aging lab at the University of Lethbridge in Alberta, Canada. Cans of soup or fluid-filled water bottles provide sufficient resistance for arm curls, she says. Grip those objects with your arms by your side, palms forward, and slowly bend your elbows to curl the can or bottle upward. Lower and repeat.

To strengthen shoulders, she says, partially fill an empty gallon milk jug with water, hold it with both hands in front of you, arms straight, and slowly raise it to about face height. Lower gently and repeat. You can do this exercise seated.

Similarly, to improve overall arm strength, re-seat yourself a few times, she says. In other words, when you start to get up from a chair, purposely sit back down and partially rise several additional times, using your arms for support and leverage.

And any time you visit the kitchen, slip in a few countertop push-ups, suggests K. Aleisha Fetters, a certified strength and conditioning specialist and author of the new book “Fitness Hacks for Over 50.” Position yourself a few feet away from the counter and lean toward it, hinging from the ankles, back straight. Grasp the edge with straight arms and bend and straighten your elbows. Complete as many modified push-ups as you can, she says, coinciding, perhaps with the length of time needed to warm your soup or coffee in the microwave. The idea, she says, is to “make fitness mesh seamlessly into your regular 24 hours.”

Even ordering seeds and starting an indoor herb garden, undemanding as that activity might seem, can “get people out of their chairs and standing and moving,” Dr. Copeland says. “Anything like that is good.”

Finally, if you prefer group activities or exercise variety, the internet is overflowing now with free exercise classes and instructional videos, Dr. Aronson says, many of them oriented toward older or inexperienced exercisers. Try a dance video if you feel vigorous and coordinated, she says, or tai chi for something gentler. Or Zoom a yoga class with friends, to stretch and reach together across the miles.