Before I found architecture and interaction design, I was and still am an avid drawer. What started out as doodles and squigglies eventually evolved into more refined drawings, after I started studying with Chinese artist, Karl Bang in watercolor, landscape drawing, architectural drawing, and portraiture.
Though I didn't know it then, I learned two important practices from him that I now abide by constantly as an interaction designer: 1) being intentional in your work and 2) refining that work through slow and steady iteration. In drawing, every stroke should count, whether to add depth, shadow, definition, etc. Moreover, every illustration should start out first with broad outline strokes, then slowly refined with more precise and detailed ones.