Harness The Power Of Meditation
As your kid grows older and starts interacting increasingly with the world around, he will have more distractions on his young mind. So you need to help him learn to settle his mind and develop his powers of focus and concentration. One way is to make your kid practice a short period of meditation every day.
Start with a few minutes of meditation daily, and gradually increase the time. Incorporate other restful activities such as deep breathing which also help to settle the mind. Make sure you do the exercises along with him so that he is further motivated.
You also need to make your child practise activities that require him to focus. For example, try activities like threading beads through a string, making a tower of blocks, or doing a jigsaw puzzle. Create a workspace for him and ensure that all these activities are carried out in this space. He will learn to associate this space with such activities, and become more amenable.