I would tell a young self - just because you love horses, don't think to make your future living from horses as so many young people think they would like to do. Stay in school, get a very good education, hopefully in something you like and will enjoy doing. That way you can afford to put money into horses and do what you think is right for them and you. Making a living from horses is tough and often you have to push them much faster and farther than is right for the good of the horses.
I never did make a living from horses but never had the money to do the things I would have loved to do, was always managing on such a tight budget.