What is most important to be a profitable trader?

The answer of the above question is "Discipline", either u have best setup or equipment, if u are not following "Discipline" u cant be a successful trader, for example i have a setup with combination of 2 moving averages on chart, my buy call will generate if small average crosses to greater average from down to up side, and sell call generates if greater average crosses to small average from down to up. it is simple, just i have to follow above rules and definitely it will work, but what if i will fall in to sentiments and avoid my signals and continuing my trades either my signal is giving exit, the losses become greater and my whole capital will be in trouble, we should always have an exit plan before entering in to any trade, and that will come from observation and "Discipline"