How about origami? I had a collegue of mine who worked with kids about that age and that was the tool she used. A simple book will have easy and harder designs to make. It will teach him all kinds of skills like self control, progressing in a sequential fashion towards an end, and give him a sense of mastery to build his self-esteem.

Books are easy to come by or find at the library, and all you need is some thin paper.
Hope this helps!!

Laura G