I'm much more of a composer than a performer, though I enjoy sharing my music with other people both ways.
My tool of choice is the piano, and my style of choice is improvisation. I like to close my eyes and let my mind wander through the forest of melodies yet to be played until I land on one I like -- and then I ride that wave until the next one arrives.
For taking a mental break from personal projects and work and sinking into introspection, I've found nothing more relaxing than the feeling of sinking into music, the sound and the feel of the instrument.
I don't play professionally, though I accept paid performances. I hope to release an EP within the next year or so, but that's an optimistic outlook at my very minimal music career.
Most of the time, I just sit and play for the same reason many people read -- to find myself elsewhere without leaving here.