ah, check for the holy grail method somewhere on this board…
here it is:
https://community.ld4all.com/t/possible-holy-grail-technique/5926
Edit:
Oh yeah um, the way you became lucid in this case is by dream sign. You remembered that you always had that song in your head and then became lucid because of it. If you do a lot of other things in your dreams, just remember: Whenever you’re doing it, do a reality check.
/Edit