In one Superman movie (the originals) Superman became a mortal so he could bang Lois Lane. Before becoming mortal he was told (by his mom I think) that he could never return, he didn’t care, he was really horny.
About 10 seconds after the deed he realised that being mortal meant that people would be able to kick his ass. So he somehow managed to get back to his fortress of solitude in the north pole and changed back into Superman.
How did that happen?