Your running/workout music player

Hi guys

I'm here again to ask a very simple question to those who can't start a workout session without a motivating playlist.
What media player/app are you using? I mean, on Android mostly.

I was wondering that it would be fantastic to have one with a great button, that you can bind to your favourite/high "spinning" song. You tap on it and it plays your song, for the moment that you need an extra incentive.