All right, if the applicant is young, tell him he's too young. Old, too old. Fat, too fat. If the applicant then waits for three days without food, shelter, or encouragement he may then enter and begin his training.
Seriously, there is no real requirements except your own excitement, curiosity and your own will. It is you, who choose to spend your time and take effort to study and practice an ancient sorcery, apply the magic and experience the true joy of engineering/creating and happiness of being in a flow..
If you will find The Great Book uninteresting and boring, feel dull and tired after two pages, or unable to see the elegance and unity of The Great Language being stuck within parenthesis, unable to grasp the ideas between them (or unable to understand why they use indentation in Python) you should leave immediately and go shopping.
We can explain the essential ideas to you and teach you how to apply them, but you should complete The Way yourself. You should form thousands of new connections and associations inside your brain. Knowing is not enough, we must apply. Willing is not enough, we must do.
So, start from right set of ideas, improve your knowledge and try again and again to do it yourself, and, eventually, you will be able to see and recognize what is good and what isn't, will be capable of expressing your own ideas in your own code or writing.