[Lurking Libertarian]

However, they do not have a duty to take you for regular medical checkups. They do not have a duty to stop you from skateboarding, skydiving, or motorcycle-riding. They do not have a duty to force you to eat a healthy diet and get sensible exercise. And so on.

At least under Anglo-American law, there is not even a duty to assist someone who is sick or injured or otherwise in peril (unless you caused that situation). If you are drowning in a lake, and I am standing on the shore holding a life preserver, I have no legal obligation to throw it to you.

[Tax-chick]

If you are drowning in a lake, and I am standing on the shore holding a life preserver, I have no legal obligation to throw it to you.

True, but I was talking about moral rather than legal duties. I have a moral duty to make every reasonable effort to save another person's life, but not a duty to make uselessly sacrificial gestures such as jumping in the lake after you if I can't swim.