Mental discipline and strength will lead to patience and skill. I like to think of discipline as the ultimate tool but not the only tool required. It takes great mental strength to pull off hero folds and calls. There is also a great amount of luck required in poker so you must be comfortable in making risky decisions even with the sake of playing disciplined. Playing "correctly" is not always the correct decision due to variance/opponent types/blind levels etc.
My other opinion on discipline; decide how much time and money you want to invest in this game. You might not plan to lose your buy-in more than half the time, but the reality of it is you probably will. Plan for having 300 Buy-ins if possible. By using discipline and sticking to that principle you will have more chance to win a significant amount once,twice, or 10 times. Using discipline as a tool for
bankroll managment will help your game for the long run.