What don't you need a license for?

[Recursion]

44. You don't need a license for most of those on private property

Driving a car? No license required on private property.

Practicing medicine is a tricky one; you can actually do most things as long as you make it very clear to the patient that you have no business doing it.

Flying a plane? You can in unrestricted airspace without a passenger

Fishing? Varies by state; you can almost always fish on your own property without a license

Hunting? See fishing

Getting married? Again depends on the jurisdiction and its status on commonlaw marriage, but this one does largely require a license (though it's not a "license" in the sense of a driver's license)

Owning a gun? No; just like a car you can own it and use it on private property in general without a license, but like a car in most states there is licensing and regulation on carrying it in public

Teaching? Depends on the district; most private schools will hire people without a license.

Practicing law? See medicine: you can for the most part do it as long as you've made it clear that you have no business doing it.