Answer:
For the script, I would suggest the following edits which can then be played out onstage:
Make sure to add that he is smiling, and describe his "wiggling" in more detail, such as restless legs, bopping his head, etc. Maybe even describe his face as "glowing with excitement" or something like that. Additionally, I would even suggest describing his attire. Bright-colored, cheery clothing would help in this case, as clothing and colors symbolize a lot as far as one's mood (yellow is often considered the happiest color).
A tip that I've been given that has helped me a lot is to describe the scene in such detail that the actor/audience can vividly picture what you, as the director, are trying to portray. Hope this helps! Good luck! :)
