I opened my own coaching service backed by a quality resume in a small city with heavy demand for this. I gave so much for little cost at first and essentially drowned out most of the competition. I raised my rates the next year and still grew. I raised them again and still grew. Eventually I opened up groups to manage the inflow and those in turn built up my client base for more personal training.
At one point, I was doing two to three clientele a day for a total of 16 clients meeting one-hour per week at $150 dollars per month. I offered the best micro-management coaching service around, possess a motivating personality, and have very fast times to back me up. Coupled with my groups, I was able to pull in about $35-$40k a year working additionally in a gym to build a bigger client base.
The gym I worked for actually bought my services to do it exclusively for them full-time, salary of $45k per year, full-benefits. I'm completely secure as this salary affords me plenty in the city I live. I probably coulda made more on my own had i continued, but the steady pay check and security is nice and now being able to do it full-time, I offer a stronger service against my prior competitors.
People ask me all the time: "Do you ever think about coaching at a High School?" and I think: Hell no. I make more than a lot of teachers and I didn't even have to go back to school for the damn graduate degree. Add to this about 10 hours of my 40 hour work week is devoted to actually running with my runners. I'll never be rich, but I have a pretty rewarding, fit, secure gig going. Add to this, if I ever lost my job, I can always return ever more experienced to what I was doing before. I'll probably never be without work again. Evey year I'm worth more in this field.