Another thing to consider... I love horses and I've worked with them for 10 years. Like had a job working with them. Every saturday I reluctantly roll out of bed to teach lessons. I really do love horses but when horses are a job its not fun going to the barn anymore. I really want horses to stay fun!! To me they are an important outlet, which I no longer have. I want to want to go outside and work with my horses, not have to get up and go outside.
I think this is an important thing that many young horse-ambitious folks don't realize. I did the working at the barn thing when I was in high school and loved it, but the pay was not best and the hours were limited even during the summer when I was free. I've seen what happens to horse people when they are overworked, and it is saddening. My old trainer is a prime example of what was mentioned- she started working with horses after graduating college in her 20s, worked at the barn doing the morning feeding/cleaning/turnout/chores and did training/lessons and massage therapy on the side. Around the time I graduated high school she began to grow weary of the life, didn't want to ride anymore, and had to turn around and find a new career in her late 40s.
Even worse is my current barn manager. She has been managing our barn since the beginning of time as far as I can tell, and within the past year had to get another barn job to help pay her bills. She used to be the kind of lady that loved mucking out stalls in anticipation of her daily rides, but now she hates the job. Because she has to work at both barns she never gets time to ride. She really wants to work with her horses, but even if she does finish her work early she wants to just sit and relax for a little while. I've seen her on a horse once since I started boarding here in May (and that's only because I begged her to ride with me :P) but before she got her new job she used to ride all afternoon. Now she needs the extra barn job to pay for her life and horses (which she keeps for just the price of feed), but she can't ride the horses because of the job. She's only about 50, so I don't know how long she will be able to keep it up or what she will do when she has had enough and wants to move on.
I'm not trying to be discouraging, but you need to be aware of how your feelings may change as you get older. You may love your horses and your time spent with them just as much as ever, but a low-paying career with them may grow very old over the next 40 years or so. If you can take a barn job somewhere, then go for it! But be prepared to be making about minimum wage. I'd suggest having a horse career on the side of something that can actually support a house, family if you choose, reasonably nice truck and trailer, shows, and your horses of course. Or, if you do go into horses, set yourself up for a life after horses. You may very well work with them right up until you die, but you don't want to have to make a difficult and trying career move when you are 40!!