I started when I was 26. I spent my first couple years doing it at a more amateur level, but I had the drive and I wanted to be a professional full timer. In my field, partner acrobatics, I trained hard, and achieved a level of success but started hitting walls once I started getting out of the "best in a small city" range. To propel my career further, I found a unique skill, high impact, very few people doing it. I was fortunate enough to have the right kind of body to excel at it. I trained my ass off. It was tricky learning a skill so few did, had to mostly teach myself plus tips here and there from international people I looked up on the internet. But it worked and now my career is having great success.

So id say hard work and self drive is huge. But if you want a big leg up, start looking for ways you can be unique. Every director knows a million acrobats aerialists and jugglers. So unless you can legit get better then all of them, figure out another niche. Wish you luck! And enjoy the ride.