In my experience, simply “being difficult” is rarely the case for a child refusing to participate. Children need a combination of modification, encouragement, and trust to participate. Here’s what you can do to motivate therapeutic participation:

  1. Modify. If a child is demonstrating an excessive amount of difficulty accomplishing a task, make the task easier (i.e., modify).  The purpose of the intervention is not frustration. It is for the child to practice important skills and master these skills as soon as possible. Therefore, make the task easier, and let the child experience success. Therapy can be difficult, but it should not be frustrating. Gradually complicate the task, so the child can improve consistently towards his goal. 
  2. Encourage. If the child verbally says, “no!”, throws the instrument, or runs away from a task that is perfectly within his abilities. Be gentle. He could be scared because he thinks he won’t be able to do it. Verbally tell him that he can do it. For example, “Yes, you can do it. You are good at playing drums. Play drums with me. I love it when you play. You can do this! You’re good at this!” Typically, in response, the child deescalates his behavior. His breathing relaxes, he comes back to the table, picks up the instrument he threw, and tries again. 
  3.  Build Trust. Trust is extremely important in the therapeutic relationship. If a child does not trust me, then getting him to try something new is difficult. The child needs to know that I am not going to ask him to do anything unpleasant. Often I will tell a child, “Ok, I have a new game to try! If you don’t like it we never have to do it again. Let’s try it.” If a child tries and does not like the game, then I will create a new activity to practice his target skills (back to modification). After a few sessions, his reluctance to participate diminishes. Even for the new activities, he is more willing to try because he trusts, from previous experience, that the therapy will consist of songs and activities that will make him feel successful. 

In conclusion, to motivate a child’s participation in important developmental tasks, you can modify the activity, provide verbal encouragement, and build trust throughout treatment.