I'm not the sure the optimal point is going to fall in the same place depending on which factors you choose to weight. It would not surprise me at all to discover that the amount of exercise I get (typically, 6 days a week, for a total of around 7-8 hours of strenuous exercise, plus an hour or so of walking /week, and I stand at my desk at work) is well above the optimum for long-term joint health or longevity, but it's right where I want it for a) strong antidepressant effect (cardio) and increased confidence (weight training) and b) increased sexual attractiveness.
This isn't hyperbolic discounting; it's just accurate discounting. I'd rather have fewer years of life with higher quality of life than another couple years at the very end where I'm alive but too old to do much of anything.
The question is - am I doing enough exercise?
I intend to provide a worked example for you to work alongside with your own calculations and decide if you should increase or decrease your exercise.
The benefits of physical activity are various and this calculation can be done for one or all of them; some of them include: