You need to be able to keep success and self-worth separated.
For two reasons.
First, because success is the outcome of many inputs, most of which out of our control. Luck, for example, plays a huge role. Others do as well, whether we recognize their contribution or not.
Secondly, because we need to be ready to maintain the same distance when success turns into failure. We are not worst human beings (or writers, fathers, marketers) merely because we are failing.
Understanding that success is not a reflection of how good we are keeps us grounded and maintains our horizon wide open. Ready to appreciate the complexity of things and continue learn from it.
Free of hubris.