For my generation (just post-Boomer), it was the TV.
For my parents, it was the radio.
For their parents, reading out loud for everyone to enjoy ("Mr. Dickens has published another episode of The Pickwick Papers!"), or playing instruments.
Problem is for the first month of lessons it is not joy, it is hard frustrating work where you sound bad and know it. Even when you are good lessons often are pushing you to do hard things and so they are not pure joy.
My son has been taking violin for years, is really good, and loves it - but most of his practice time is still really hard pieces that need a lot of practice of the hard parts (stitching between 5th and 2nd position...) and he would prefer to sit down at the piano (he stopped lessons years ago) and play an easy piece.
Practicing is always hard and I struggle to find time or energy to push myself but my goal was to be able to play basic chords and make up silly songs around the campfire so everything else is just a bonus.
For my parents, it was the radio.
For their parents, reading out loud for everyone to enjoy ("Mr. Dickens has published another episode of The Pickwick Papers!"), or playing instruments.