"Do the uncomfortable."
This advice came from my mentor at my first "career" job--the man who taught me to be a lawyer. Only he never actually spoke those words to me. Instead, he simply put me into situation after situation.
Sometimes, when you are in uncomfortable situations...you feel uncomfortable.
I recognized then that it was intentional. He didn't tell me to take on challenges that intimidated me. Instead, he dumped them in my lap. One gift after another, and I've been grateful since.
The remarkable thing about doing things that scare you is that once you experience that feeling, you go looking for it. Because the sensation of coming out the other end is fantastic. You learn that facing big fears results in the big payoffs. Fear is not the same as "risk." In fact, many of the things we fear are not necessarily risky.
On the other hand, some of the worst advice I've ever heard says "play it safe. Stick to what you know." Playing it safe makes sense sometimes, but if it's your default reaction, you run the real risk of denying yourself fulfillment and achievement.
Imagine if Steve Jobs said, "Let's stick with computers, who cares about phones, or music?" Or if Oprah Winfrey said, "I love being a local news anchor, what else is there?" And, if Elon Musk woke up tomorrow and said, "Paypal was great, I'm done."
Do the uncomfortable things that scare you, and your success will find you.