A lot of people here with a lot of experience and knowledge already shared the importance of discipline. I would like to put a huge emphasis on the concept again.
It is good that you have mentioned in the beginning you followed your system to the every single last detail and you were up at first. This is a good point.
Once you develop a trading plan or a framework, you backtest it, you adjust it, you prepare it in a way that it is a full scale pipeline of processes and protocols that needs to be followed in order to generate ideas, size them up, prepare your positioning and sizes, time your entry and exits, thats what you absolutely have to do. Follow it to the last drop of discipline.
Keeping a journal is also mentioned many times, it is a good point as well. It fortifies the habit of sticking to your plan and incentivizes abiding by your predefined framework. It also shows you where you left loopholes or made mistakes, so, keeping a journal in and of itself is not enough, you have to regularly go back to it and review it at different levels of experiences.
Removing your ego completely is also another issue. You should listen to anyone with experience to see if you can learn any bit of a new information from them. You don't have to completely scrap your mental models and start from scratch, you do not have to go back to square one. You can pick up a whole lot of beneficial details and tweak your systems along the way. Add them in where you see fit.
I can go over a lot more but I think these will cover the basic pillars of discipline. Expectations, patience, dedication and treating it like someone else's money are also good fundamental tenets and valuable ideas for having discipline.
