Why is it important that you start assuming responsiblity for your personal health and choices?
Because it shows you're mature enough to decide such things for
yourself - instead of having an adult choose for you.
Also, you consciously take responsibility for whether you have
good health or poor health, and therefore take personal action to;
work toward better health, get to know your own body, or make
decisions about which path to take if working out an health issue.
The important thing is that it's your body, and when you assume
responsibility for it, YOU decide.