How to deal with startup stress..

I think a lot of these are true in general - rather than being specific to startups...

However, aiming for zero stress or "dealing" with stress is probably unrealistic and counterproductive.

Most people need to maintain a level that keeps you productive and engaged. I use the metaphor of your heart-rate during exercise. If you're doing a run you want it high, but in a range that you can sustain.