Exercise is a long term investment though. Life really is easier when you're fit. And all the gains you get in your younger years cannot be easily done when you

Exercise is a long term investment though. Life really is easier when you're fit. And all the gains you get in your younger years cannot be easily done when you're older especially for muscle mass. This specific amount of cardio fitness is probably not strictly needed. Given the choice I believe most people should chose more strength training. But at any given time, being able to pop out at least a 5km run or equivalent is probably a good place to be.