To make your art great, one must always be in a mode of attack. It's the same frame of mind you put yourself in when critiquing others work. Once you fall in love with it, it becomes too precious to even think about touching.
Belief is one of the most potent and powerful human abilities. Belief can accomplish unbelievable things, some of these things through simple alteration of our own brain's chemistry. When we truly believe in our abilities, something changes in us physically. Synaptic connections re-route and conform, and before you know it that belief has become a fact. When we believe in ourselves, those around believe in us too. It's evident most obviously in our confidence, but also in an infinite amount of undetectable behaviors that others pick up on subconsciously. Suppose you wished you were an incredibly good fighter. The first step is to practice, no doubt. However, the next is to BELIEVE you are a great fighter. When you truly believe this, your behavior will change. You start to believe more and little things start to fall in to place. The way you walk changes, you're more confident. Maybe you walk like a great fighter. You sit smugly when someone taunts you.