In his book Mastery, Robert Greene talks about what separates amateurs and masters:
By nature, we humans shrink from anything that seems possibly painful or overtly difficult. We bring this natural tendency to our practice of any skill. Once we grow adept at some aspect of this skill, generally one that comes more easily to us, we prefer to practice this element over and over. Our skill becomes lopsided as we avoid our weaknesses. Knowing that in our practice we can let down our guard, since we are not being watched or under pressure to perform, we bring to this a kind of dispersed attention. We tend to also be quite conventional in our practice routines. We generally follow what others have done, performing the accepted exercises for these skills.
This is the path of amateurs. To attain mastery, you must adopt what we shall call Resistance Practice. The principle is simple—you go in the opposite direction of all of your natural tendencies when it comes to practice.
First, you resist the temptation to be nice to yourself. You become your own worst critic; you see your work as if through the eyes of others. You recognize your weaknesses, precisely the elements you are not good at. Those are the aspects you give precedence to in your practice. You find a kind of perverse pleasure in moving past the pain this might bring. Second, you resist the lure of easing up on your focus. You train yourself to concentrate in practice with double the intensity, as if it were the real thing times two. In devising your own routines, you become as creative as possible. You invent exercises that work upon your weaknesses. You give yourself arbitrary deadlines to meet certain standards, constantly pushing yourself past perceived limits. In this way you develop your own standards for excellence, generally higher than those of others.
In the end, your five hours of intense, focused work are the equivalent of ten for most people. Soon enough you will see the results of such practice, and others will marvel at the apparent ease in which you accomplish your deeds.