Disciplined has different meanings to me.
The act of withdrawing from something can be called disciplined, e.g gambling.
The act of trying over again and never giving up can also be called disciplined.
My advice is you better find something that works for you, trading won't work for everybody, because we can't all be disciplined with trading, controlling emotions and losing money only to go back in again is not something that everyone can get used to, I am talking from experience, there are many people who wished they are never introduced to trading at all.
Having discipline is knowing what you can do the best and setting aside what your knowledge and skills do not fit. So if you are good enough to trade and has the real capacity to make a positive trade, then try it and hone your experience. But if you are like others who are into losing often times and have never experienced even a single profit, believe me trading is not for you.
Discipline develops but it takes time. So if you are actually interested to trade, take your time, commit mistakes and eventually learn from it. If you grow from it doing, its worth doing continuously, but if not, leave trading and go where you mostly fit and make positive income.