+ Increase productivity (e.g. if value = work x time, and you can't increase available time, then reduce time consumption per unit of work to increase value)

+ Increase comfort during this process

- cost: available time is reduced, which you could have spent working.

Objectives to exercising:

+ Increase lifespan

+ Increase comfort(health) during this lifespan

- cost: available time is reduced, which could have been spent living

Tbh, these look pretty similar to me. In both cases, you're trading off an existing resource gambling that you'll get back more than you put in.

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As an addendum, there's a right and a wrong way to achieve tradeoff-based objectives.

With exercise/diet, you can certainly do it wrong: latest fad diet that's placebo or maybe even actively harmful to you, latest fad routine that isn't very efficient, overwork and hurt yourself, etc.

If you're "wasting a bunch of time" customizing your computer, I guess you're doing it wrong. Certainly, don't do that.