The theory that a trader must have to be successful is almost known to all traders but not all are able to carry it out well, about discipline sometimes traders will break it even a soldier who is used to discipline will also find it difficult to remain disciplined when becoming a trader.
Intellectual or skill about trading is what traders sometimes do not have so they trade like gambling just following feelings and eventually lose everything.
To become a quality trader we must continue to evaluate what trades made us lose that day and vice versa.