We know from science that the brain maps reality so that what it “sees” as an image is as real to it (and you) as any other experience you have–whether it occurred only in your mind, or you physically experienced it.
Do you have a grapefruit in your mouth? Try this: Imagine that you do. Take a moment and see yourself slicing through the dull orange-bright yellow outer skin, exposing the sections on the inside. Now see yourself holding a section in your hand and putting it into your mouth. Can you feel your saliva glands reacting, generating extra saliva —not in your “mind’s eye”, but actually in your “real life” mouth?
So for me, the many experiences I’ve had which seem to defy the known laws of physics–like waking up floating, being able to put my body through solid objects or flying through the air–are as real to my brain as sitting here now. There is no difference.
This also means that you can use imagery to do things like heal parts of your body by seeing them healed.