"Master yourself master the enemy"

I read this article explaining what Lee sin quote means however I think it does a terrible job so I want to elaborate here. Here's the link for reference: http://forums.na.leagueoflegends.com/board/showthread.php?t=2953997

In the thread it's mentioned: "It means, you cannot master your enemy until you master yourself..."; while yes this is true it also has a deeper meaning: you are your own greatest enemy and if you can master yourself you have mastered the greatest enemy you will ever face, you.

This is one piece of advice largely missed when trying to improve at league or really anything in life. People often wonder what is holding them back. I truly think it's themselves and they have key points about themselves that they struggle with and it's these parts of themselves that is truly what holds them back from accomplishing more.