This line of thinking can be good motivation sometimes (like when you're wasting time commenting on HN and should be working instead, oops), but other times it

This line of thinking can be good motivation sometimes (like when you're wasting time commenting on HN and should be working instead, oops), but other times it can be a burden on your psyche. If you always think in terms of "how much is this activity costing me per hour?" then you will never let yourself do anything fun or relaxing because the guilt will be too much to let yourself enjoy it. Having fun and relaxing to prevent burnout is equally important to making your startup work, otherwise you will drive yourself (and the business) into the ground, in which case everything is worth $0 anyway.