Irwin Greenberg (Greeny), one of my teachers at the High School of Art and Design used to say that "Habit is Stronger than Will". He urged us to develop a habit of drawing or painting each day regardless of what other things we had to do. Greeny would stress the importance of putting our time in to advance our artistic growth. We get in the habit of other daily rituals for the sake of our physical, spiritual and financial well being and as artists we should have a "habit" for our creative well being. It doesn't have to be grand or time consuming, it could be a sketch or some thumbnail concept sketches, a small watercolor or oil study.
Over 30 years have passed since I was in a class and heard that bit of advice from Greeny. Sometimes it takes maturity to understand how meaningful and life changing a few words of advice can be.
If we only work on our art when we have the "will" to do it, our output and growth as artists will be tied to the strength of our "will", if we make art one of our habits we will see a direct correlation in our work.