You cannot win the war against the world if you cannot win the war against your own mind. Self-discipline is the center of all material success 99% of people are not leaning to do what it takes to make their dreams come true, the sailor have a saying that everybody wants to go to the heaven but no one wants to die.
Self-discipline something as simple as food and eating, is not about your body as much as it is about your mind its getting command of your mind to be able to choose actions that are in your own best interest.
A lot of people just trying to change lots of time but do the wrong thing. If you win the first time of a day you win all the day, every day we are choose bullshit things that not our own best interest, a very strong research say that you can only make a certain amount good decisions a day and after that spent you cant anymore and that’s why you know people like Mark Elliot Zuckerberg wear the same T-shirt because they don’t want spent time for a decision that’s not very important. Its not necessary to know all the good and bad news, and you should have a discipline in your and think about your goals and take the best decision in the first of the every day.