I have the choice of being constantly active and happy or introspectively passive and sad. Or I can go mad by ricocheting in between.

This quote means that people have a choice in how they think and behave. They can choose to be cheerful and active, feeling good and interacting with people and the world around them. Alternatively, they can choose to be introspective and sad, withdrawing inside themselves and avoiding the world outside. Or they can go between being active and being passive, which can make them feel confused and overwhelmed and eventually lead to madness.