Issues. Confusion.

try thinking about others, give some service, volunteer. worked for me at your age.

Start thinking about college. Take some classes and see what interests you once you graduate.

I am 27 and that's what I am currently doing. It's a bit late in my life to just be starting but at your age I was a HS drop out who was living with her 22 year old boyfriend and eventually got pregnant at 17. I didn't have the advantage of being free to do whatever I wanted, I was too busy changing diapers and losing sleep while I was still a teenager. My going to college has made me realize what I may want to do as a career.

Fitness: Just start.  Do anything.  Walk, take a yoga class, treadmill, elliptical, weights, hiking, whatever ...  The activity itself doesn't matter.  Just try to do something every day.  The key is to mix it up and keep it fresh.  You're much more likely to stick with it that way.

Live: At 16 you're probably not supposed to know what you want to do.  Like SS said, focus on getting to college.  I know that seems an aweful long way from here but it isn't.  In the mean time, like chang said, volunteer, it'll help give you some direction and tell you more about what you like and don't like.

Good luck...

-Dennis-