This is just me talking, but I get a complete physical every couple of years. They test everything (yes, there too!) and give me an EKG. My blood panels usually cover the normal things like lipids, cholesterol, liver function, thyroid, stuff like that. Your doctor will recommend stuff based on your family profile. If you want to have some fun, ask for a treadmill test and see what level you get to.
3 years ago, I got to level 6 or 7. Better than some firefighters the doc tested!
As for the bone density; you're 23. I seriously doubt you have issues there, unless there's family history.