I play the classical guitar, and here is what it does for me.
It motivates me because I was not able to hold it properly when I was 200+ pounds. It gets me out of the kitchen/pantry and into the music room. It keeps my hands busy (both are required to play). And, I would not think of snacking when I am holding the guitar, can you imagine cheetos crumbs falling into the soundhole? Finally, the music gives me a deep emotional fulfillment so that I do not have to fill myself up with food.
Musical instrument required, does not have to be a guitar. Playing, even simple material for beginners, increases self esteem big time. You can create beauty.