Exercise does not have to be prolonged to be beneficial. It just has to be frequent. Several times per day
From NYTimes : "Walk for two minutes. Repeat 15 times. Or walk for 10 minutes, thrice. The benefits for longevity appear to be almost exactly the same, according to an inspiring new study of physical activity patterns and life spans. It finds that exercise does not have to be prolonged in order to be beneficial. It just has to be frequent." The scientists found that moving strongly influenced longevity. The more often you move, the longer you live. References: Those 2-Minute Walk Breaks? They Add Up. NYTimes. https://www.nytimes.com/2018/03/28/well/move/walking-exercise-minutes-death-longevity.html