Everyone who's taken on a trade or tried to learn a new practice knows that you've got to care about it--
really care about it--and be glad to improve it. Otherwise, as time goes on, you notice imperfections in your work that make you really upset, grasping new concepts becomes more difficult, and practicing becomes tiresome and even
boring sometimes. That's when the temptation to quit shows its deceitfully relieving and tempting face.
You've got to have passion for what you do--not just thinking
"I have to do it", but taking heart and really enjoying doing it. Knowing that it's not for nothing.
For a writer, every paragraph written with eagerness and attentiveness creates a heart-felt passage and flexes their creative muscle. Every song a pianist practices faithfully keeps their fingers flexible and produces beautiful, harmonious sound. Whenever an actor works hard and gladly in the play/musical/opera they perform in, they gift an audience with a real and heart-felt performance.
When someone really cares about what they do, and they put all they've got into it, the work can really be amazing.