I automatically resist claims that there is, for instance, one single thing that makes people successful/rich/attractive* (*delete as applicable) because there isn’t. But the Inc website makes such a claim (via Lifehacker) and it is persuasive. I’m sure there is more to it but I could be convinced that this one thing is an essential part of being successful:

The only major personality trait that consistently leads to success is conscientiousness.

This is the Personality Trait That Most Often Predicts Success – Inc

Besides, I like it. I like that this is successful trait. Read on for some statistical research and more detail.