I remember becoming interested in art when I was very young and started drawing comic book characters. When I was a young teen, I bought a paint by number set and when the printed cards were painted and I had left over paint, I didn't want to waste it, so I drew on cardboard and painted until it was gone. Needless to say, those paintings didn't survive the years.
Although I love all art form, watercolor is my preference. And what subject to paint? Just about anything that inspires me. If I find myself 'seeing' the form, color, light and shadows... and wondering 'How would I paint that?' I am likely to spend some time trying. Interestingly enough, some of my favorite paintings were done in a relatively short period of time.
If I can paint something that brings a smile to someone's face or a sense of wonder to their mind, then I have acheived my goal.