A lot of this is extremely speculative, but it’s also just a ballpark estimate for my own amusement.
I wanted to know the benefits of working out in terms of lifespan gained vs. time spent. Is there a benefit when compared this way? The best science out there seems to be point to a lifespan gain of 4-9 years of at least three times weekly resistance training vs. sedentarism.
Assuming that I spend three hours a week working out, how much time is this, assuming I live 40 more years? Turns out it’s about 37 weeks — about three quarters of a year. Note that is actual time working out only.
Say this amount of working out extends my life five years — a good middle ground as compared to the science.
Using the figures from above, this means that for every hour working out I would gain approximately 6.5 hours of life span. So, yes, resistance training “buys” quite a lot of extra life as compared to time spent.
Obviously this sort of calculation does not really apply to an individual. I could have an undiagnosed heart problem that kills me in 5 years. I could be run over by a car in Florida. Etc.
However, it was fun, and I also wanted to know in the general case — using the best available science — if you were gaining anything time-wise in principle from resistance training. And yes, you definitely are.
This does not at all take into consideration hedonistic improvements from working out — that you feel better, think better, and can do more. With this in mind, resistance training might be worth it even if it in fact diminished your lifespan.