Beset by doubts, they often start fighting their own goals even before they have a chance to get started. Eventually they risk less and less, and become motivationally flaccid and timorous. Successful people aren't afflicted with a sense of guilt when they achieve even higher career goals. Their successes are meaningful because they meet the standards of their own internal measuring rods. Their expectations don't reach beyond their accomplishments.
Guilt often is a form of self-disappointment.
It happens when a person feels he has fallen short and somehow betrayed some internal sense of potential. Their work fulfills the broader goals they want to achieve in their lives. They're able to enjoy their career accomplishments in a realistic way. While critical of their own work, they're never supercritical and thus don't make things harder on the job than necessary. They're honest with themselves and appreciate their strong points.