I've been a successful freelancer for 10 years. I still feel like I should always be chasing my next opportunity.

The author (not pictured) has been a freelancer for nearly a decade. Luis Alvarez/Getty Images I've been a freelancer for nearly 10 years, and my career is stable. However, I always feel a low-grade uncertainty. I make sure I'm constantly adapting along with my industry and looking for new opportunities. When I became a freelance writer nearly a decade ago, I assumed the uncertainty would eventually fade. I imagined there would come a point where I'd built enough relationships, landed enoug...