*Playing by ear* I hear a song and I go, "I wonder if I could
play that?"* and I mess around for a few minutes until I'm like,
"Ok, GOT IT!" Some are tricky for no particular reason.* The
chord progression for "Radioactive" from Imagine Dragons stumped
me for a few minutes, as did the chord progression from one of
the Minecraft songs a few years back. But once it "clicks in" -
it's like unlocking a door and stepping through.