Diehard

This feat was heavily inspired by the 3.5 feat of the same name.

You've got the spunk to resist even death itself, when you take lethal damage that would reduce you to anywhere between -1 and -9 hp, you can choose to go into a disabled mode instead of going unconscious. 

While disabled, you may make one action per turn or move at most 10 feet.

If you attempt to make any other actions other than your singular action, including bonus and free actions, you automatically take 1 point of damage.

If you reach -10 hp while in disabled mode, you immediately die.