I learned an enormous lot of songs back in college days by the marvelous invention of a automatic replay on a tape deck - it kept going, reversing to the other side every time it hit a metallic sensor on the tape. So I left it on while I was studying or doing dishes or whatever and after 7-70 repetitions I could sing along with every word/whistle every tune.

I assume you can do the same with CDs and I know you can with some record players - set to "repeat" and just leave discs in/take with you on portable player. Saturate yourself with tunes you like. About time you get tired of hearing them, as noted above, it'll be because you can play/sing them all the way through.

Best of luck. Elaine.