You may try the positive reinforcement method. Basically, desired behavior, when praised has a chance of being repeated. Try to acknowledge any efforts and results as often as you can.
Building a self-esteem might help in all areas.
You may want to address this with school. Most public schools have support that may benefit your child. At least find out if the teacher can introduce any reward method - allow for a fun activity, etc. It is not easy, but worth trying.
My son, 7, already has special aid in a class and they continue to work on different methods to keep him motivated and happy about himself. It does not always work, but we are happy when it does...He has number of medical attentional issues, but the classroom methods are helping him to stay off the medication... At least for now. He also works with school psychologist to address any emotional (self-esteem) issues.
We had to change a school to a public system to get this going - but as hard as it still is, we can see results.
Try him on a supplement,,,all children and especially those with concentration difficulties benefit from a Multiple Vitamin-mineral supplement with antioxidant Vit B Complex and Vit C also parents say fish oil works , this has been shown (according to some experts) to have the same efficay as Ritalin. I also think nutrition counts,eliminating allergic foods then adding them back to see if he is having a reaction, Dairy and wheat ,black list colourings and sweetners as in Diet sodas , preservitives. ,Good luck Google for more information on Nutrition,