the hardest job

Self discipline.

Self control.

To have the discipline to get things done you have to have the control not to do things that aren't good for you.

Before you can control the conditions of your life you must control yourself.

Man do I ever want a chocolate bar right now.

No, really, I don't. I have beaten that weakness for the time being. But it does cross my mind so I haven't beaten it completely.

It is the hardest job you face, just controlling yourself.

This is the one thing that you absolutely must beat. If you don't then it will beat you and all your other work will be of little value.

Think of something you indulge in that you don't need and that isn't good for you. Set your sights on that one thing and beat it.