I don't really feel like an adult. Or, to be more precise, I don't feel like I used to think adults would feel when I was younger. I guess I must have associated "adult" with "serious" at some point. As a much older person once told me, I have a very developed sense of play.
Jumping up as the elevator is going up, trying to catch the right moment to get a little bit of freefall, is still fun. However, I only do it when I'm the only one on the elevator. I wonder what reaction I would get if I did that when other people were there. Maybe the same reaction I get when I ride on the grocery cart in the parking lot of the store.