Jonathan Cronin argues that discipline means doing what you don't want to do, not what you enjoy. He points to Jesus as the example: Jesus gave everything, endured extreme stress, and relentlessly pursued his mission. Real discipline requires sacrifice to unlock God's blessings.
Chapters
It doesn't take discipline to do things you like. We all understand discipline is the key to unlocking the things you really want in life. To achieve all the things that God has for you, it takes discipline. However, discipline is not doing things that you like to do. Discipline is doing the things you don't want to do and continue doing them. The deepest calling is to live as Jesus lived, which is passionately, obsessively, over, and relentlessly pursuing the thing that he's called you to do. His life was giving everything, sacrificing everything. He had moments of stress beyond belief, and it was this life of ultimate sacrifice for the reason that God had him on the earth: forgive sins and be able to make a way for people to be saved.