Music, like any other highly competitive field, always comes down to perseverance. No matter how talented you are or how how much success you've had in the past, there are times in everyone's career when perseverance is the only thing that will get through. If I were starting a group or music based business today, the quality I would most search for in any potential partner is perseverance. Those who always seem to "catch a break" have perseverance in spades, while those who never seem to don't.
If I were a principal and hiring a band director, the quality I would most look for in a candidate is perseverance. Every single band director I know who seems like they were put on this earth to teach band has an unrelenting sense of perseverance and determination.
The best way to learn this trait is to hang around those who possess it. Seek those people out, both as partners and mentors, and you will go a long ways in the music business.
Perseverance always wins out. Always.