I believe it only feels real because your mind is free thinking and all knowledge of reality goes out the window. I've had dreams where I could fly, or have super strength, or breathe underwater, and never even had a second thought of "I can't do this in RL" lol (The breathing underwater thing I had when I was younger and I actually tried while in a pool [in my dream it was more like a fish opening its mouth and I breathed that way, so when I was actually in a pool, I just did the motions like a fish and it didn't work, but I could've sworn it was real]). However, that's the trick to becoming lucid is to recognize that what your doing doesn't make sense and that you must be dreaming