I'm only responsible for what I say, not for what you understand. Although as an author I am responsible for making readers understand--a reader who doesn't understand is an unhappy reader. (And there is some value to leaving some questions unanswered.
I need a stability ball. A stability ball is a great addition to standard workouts as they help core muscles to activate. Core is what supports your posture and daily functions, but often overlooked and underutilized while working out.