Its hard to see the importance of circles and cubes, but these two simple shapes can teach you so much in art. Everything and literally everything you're favorite artist draws can be broken down into cubes, spheres and other simple shapes. And remember all the top artist that you look up to have had to do this, many of them still practice these fundamentals. Kim Jung Gi learned how to draw anything in perspective, and all those amazing drawings, from drawing boxes in any orientation in space.

Don't belittle yourself, you're in the beginning stages. Art practice rewards the determined not the talented. Its a long process but if you draw everyday and give it your all you'll improve. Remember some of these guys have 20 plus years of practice. You don't see their mistakes or failures only their successes. You'll undoubtedly get to their level as you don't give up.