This is what joy looks like when you’re seven years old. Why is my grandson Griffin jumping with it? School. He loves school. May we all be so elevated by learning.
Speaking of learning, a good way to learn about the protagonist in your story is to ask them: What makes you jump for joy? If not literally physically, then at least in your heart? And if not literally physically, then why not? What stands in the way of joy unbridled? What past wounds make it hard to express positive emotions? The more we know about what our characters have been through, and how it manifests in their life, the more authentic we can make them on the page. Then the reader will be jumping for joy with a good book in their hands.