30!!! Adult? Feel about 12!!!

Do any of you feel a lot younger than your years? I'm 30 (?!). I feel about 12 a lot of the time. I walk, and feel like running, there is a spring in my step, an energetic need to jump, to dance, to giggle. Conversely, I sometimes get an extreme sense of immobility, when my legs feel like lead and are hard to move. It's either one or the other, with me. The intense energy tends to come first thing in the morning, and often after an interest binge. I feel about 5 ha!. How can I be 30? Adult? What?