A recent study was conducted to see if a correlation exists between exercise frequency and days of missed work.

It was found that the people who exercised at least 20 minutes once a week had significantly less missed workdays than those who didn't exercise at all.

Those who exercised at least 20 minutes, twice a week had even less missed workdays than those who only worked once a week. What does this mean for you? Exercising twice a week can improve your tolerance for your regular activities of daily living.

References
Workout for work. Journal of Occupational and Environmental Medicine 2001; 43 (12):1019-1025.