Ways to not burn yourself out:

"Ambition becomes counter-productive when you pursue your goals without the humbling realization that things seldom go as planned."

"As you seek to utilize your productive capacity to its fullest, always keep a reserve. Plan it into your day as well as your philosophy. Ambition is a fine thing, so long as it doesn't override opportunity."

This advice is from Scott Belsky, the CEO of Behance and author of the national bestselling book Making Ideas Happen, and quoted in this article about why we all need a margin for error.