At any point in the game make your cursor into a skull. After that,
press the left-Shift key + the F9 key. Hit both at the same time. You will
still take damage, but when your energy goes down to 01 you stop getting hurt.
Sometimes this toggles the characters voices. Don't worry, just hit
the F9 key to get the sounds back.
Thanks to Revolution readers Todd's Friend and Stephen Straube!