I work with a lot of talented and ambitious people, both in my consulting and nonprofit work.
I see a pattern that absolutely kills people, that most everyone that's got is oblivious to.
It's rapidly adjusting to new successes, giving oneself minimal credit, and adjusting to that as a "new normal" -- and setting a new baseline of "required" performance off of that.
So let's say someone wants to be a writer, and they start to get in a groove and write 7,000 words per day. If you've got this mentality, you'll very quickly say, "Ok, I've done 7000 words per day. That's normal. Now, every day less than 7000 words is weakness and failure." No celebration, no reflection on the success, just ratcheting up the difficulty level.
The same thing goes in sales, business development, entrepreneurship, technology, all kinds of creativity, all kinds of training.