I was very fortunate. I was born into a horsey family and had a professional trainer for a dad. Because of that, I always had good horses and learned early how to turn out a good horse. I started putting miles on green horses of Dad's when I was about 11 or 12, and worked on greener and greener ones. I sort of jumped into training one on my own at 14. He ended up broke as he could be, but due to my own inexperience and lack of knowledge, he doesn't have really stellar training. He's hot, chargey, touchy, and difficult to ride.
After him, I kept on finishing off greenies for my Dad and I would start the more mellow ones on my own (under his instruction since these were his customer's horses). I steadily worked up from there, handling the greener "problem" horses and worked my way up to starting them from day 1.
During all that, I started taking in a customer horse of my own here and there during high school. After I graduated and moved away to the city, I didn't get much time to get home to ride, but I still would put a few miles on someone's green horses whenever I was home. Then, when I moved back home to start training full time, my business was all ready to go great guns...and it did. I kept a waiting list anywhere from 2 to 10 months long and I stayed busy.
I decided earlier this summer that I wanted out of it. It was starting to feel too much like a job because I had to take on more horses than I really wanted just to be able to afford decent health insurance. Not to mention the unrealistic expectations of so many customers.
Too many people have seen movies where someone loves a horse into being broke in a week...so that's what they expect *eyeroll*. Then, they don't follow your instructions for when they take the horse home and get pissed at you when the horse doesn't stay broke.
Just as a perfect example, my last customer: He sent me a 3 year old horse that he had turned into a bucker. EVERY TIME you put the saddle on, he turned into a saddle bronc. If you let him stand still for more than a couple minutes and then asked him to move off, he turned into a saddle bronc. He was pushy and obnoxious on the ground.
Because I know I'm not a bronc rider, I worked with the horse for quite a while on the ground before I ever got on him and it was about 2 weeks before I even took him out of the round pen. Still, in 60 days, I could saddle him, step on, and ride off with no problems, lope circles easily, neck rein, leg yield, sidepass, etc.
I sent the horse home with explicit instructions that someone needed to ride the horse every day to keep him going or he would likely revert to his previous behavior.
Fast forward to 4 months later, I get a phone call with this guy telling me how upset he is because he took the horse home, turned him out for 4 months while feeding him about 10 pounds of sweet feed per day, then wondered why the horse bucked again when some stranger tried to ride him to move cattle at the sale barn with no warm up or anything
So, now I only train for a hobby and am considering just keeping to my own horses.