Wallpushups are good but if it isn't a possibility he might try pushing his hands together hard, or carrying a stressball type thing in his pocket. Anxiety strategies like deep breathing or learning to tighten and then relax muscles may also help. There is quite a bit written about the "mental game" sports and how athletes can learn to focus for best performance. Maybe some of that information would be helpful to him.
I know parents vary in their approach to lessons. I am unwilling to pay for lessons unless the child practices consistently. I consider it a minimum responsibility.
