Magic Box Exercise

Over at ChrisOatley.com, I'm taking some painting courses at the Oatley Academy to BRUSH up on some painting techniques. The first exercise he's having us do is getting a grasp on atmosphere and lighting by observing soft shadows. Avoiding the crisp shadows made me realize how encompassing soft shadows can be which proved to be pretty difficult me to execute. Here is the photo reference I used along with my attempt to duplicate its atmosphere: