As a founder, your own emotional health is another key metric you need to manage, and you need to treat it as such.

I rely on three simple interventions:

1) Get a good night’s rest.  Failing that, take a nap.

On
days when I haven’t had enough sleep, every problem seems like a
mountain, and every setback makes me want to curl up into a ball.

On days when I’ve slept well, every problem seems surmountable, and every setback is just another opportunity to overcome.

Get sleep.

2) Eat healthy and regularly.

Your
body is a machine.  You wouldn’t expect your laptop to perform well if
you stopped charging the battery and repeatedly dropped it on the
ground, so why do you treat your body that way?

A
study of Israeli parole boards showed that these very tough customers
(Israeli, remember?) granted parole to less than 10% of prisoners who
appeared right before lunch, and over 60% of those who appeared right
after lunch.

Saving a few minutes by not eating is insane.  Keep the machine fueled.

3) Talk with friends who energize you.

We
all have friends who make us feel happier and more energetic.  Taking
the time to enjoy those relationships and their company isn’t
selfish–it’s the cheapest form of therapy the company could buy for
you.  Sometimes, the best way to solve a problem is to set it aside to
rejuvenate yourself.

TL;DR: Sleep, eat, and spend time with the friends who energize you.

P.S. If you are experiencing actual clinical depression, for goodness sake, seek professional help.  Nothing is worth risking your health or your life.  I wish my friend Jody Sherman had done so.

P.P.S. A version of this post first appeared as a Quora answer.