At a dinner party, someone was cheerily justifying the piles of money he spends on a personal trainer. He’s feeling so great that it’s worth every cent, he exulted, “And the best part is the return on the time! Every minute you spend working out comes back to you, because you’ll live that much longer!”
Here is the math by Tom Anthony who holds a Harvard physics degree:
Computing years of life gained after age 40
Running for two hours a week should gain you about four years of life. “So that is roughly 100 hours per year for your remaining 40 years or 4,000 hours in total for all 40 years. In one year, there are 24 hr/day X 365 days = 8,760 hours. So four additional years is 8,760 hr/yr X 4 yr = 35,040 hours of life gained. To gain these extra hours, you expended 4,000 hour of running. So the payback ratio is 35,040 hours gain/ 4,000 hours expended = 8.8.
Running for an hour gives you 9 hours of extra life.
Brisk walking for an hour gives you 2.9/8 X 9 = 3.2 hours of extra life.
Biking for an hour at less than 10 mph gives you 4/8 X 9 = 4.5 hours of extra life
Rope jumping for an hour gives you 10/8 X 9= 11 hours of extra life
Calisthenics for an hour gives you 8/8 X 9 = 9 extra hours of life
Source: Common Health