I have a tiny Sansa Clip+ mp3 player, flashed with Rockbox, which I use with a nice pair of Bose wired earbuds. It's an incredibly low-friction device. It has physical buttons so you can operate it without looking at it. It lasts for multiple days of continuous play, and I'm not an all-day-every-day kind of listener, so I seldom worry about charging it (and wired earbuds don't need charging either). It's got a 512 gigabyte microSD card in it, so for all intents and purposes it can fit unlimited music, and copying music to it is trivial. It masses 24 grams and can sit in a top pocket without weighing it down. It exists completely independently of my phone, laptop etc, and so I always have my favorite tunes (and an FM radio) wherever I go.

Single tasking devices are great.