What did Gatsby do as a child to help himself become a success?

Gatsby kept a regular schedule for himself, even as a child, to ensure that he would better himself consistently, develop a strong work ethic, and waste no time. He would "Rise from bed" each day at 6:00 a.m.; no sleeping in and wasting the day for him. He would then work out for fifteen minutes, study for an hour, and then work for eight. After work, more exercise via playing some sport for thirty minutes, and then he would "Practice elocution, poise and how to attain it" for one hour. Finally, he would "Study needed inventions" for two hours before bed.
Gatsby also created a list of general "resolves" for himself, in addition to this rigid and well-rounded schedule. He wrote that he would not "waste time" at various locations (perhaps pool halls or bars), he would not use tobacco products, he would take a bath every other day, he would engage in the regular reading of improving materials, save money regularly, and be "better to parents."
Between his schedule and his list of resolves, Gatsby seems to really hit all the bases: he wanted to make the best use of his time, to engage in some physical activity, to be creative, to work hard, to not spend precious time and money on activities that would decrease his ability to do everything else (drinking, smoking, etc.), to be clean and well-rounded, and to be kind. Surely, it seems that a person who has all of these qualities ought to be a success. However, the fact that Gatsby eventually must engage in illegal activities in order to become that "success" seems to indicate that there is something broken in the American system, that, perhaps, the American Dream is only a beautiful fiction.

Gatsby's determination to better himself is made evident in the daily schedule he devised for himself, along with a list of the "general resolves." He wrote them on the last, blank page of a copy of Hopalong Cassidy as a boy, and Mr. Gatz shows this to Nick in chapter nine.The concept is likely inspired by Benjamin Franklin's pursuit of "moral perfection" as outlined in his autobiography; it, too, has a daily schedule and list of desired behaviors and qualities he called "virtues."
According to young Jimmy Gatz's daily schedule, he would rise at 6 a.m. to exercise for thirty minutes. He would study for an hour, work for eight hours, exercise for another thirty minutes, spend an hour working on "elocution" and "poise" and then study "needed inventions" for two hours before bed.
The "general resolves" include not wasting time, avoiding tobacco, bathing, reading, saving money, and being "better to parents."
In short, Gatsby developed goals and the discipline it takes to see them through.
Fitzgerald, F. Scott. The Great Gatsby. Charles Scribner's Sons, 1925.