I go through hobby "phases," for lack of a better word.
I mean, sometimes it's a cooking spree, sometimes I'll go off on reading expeditions, sometimes it's music and sometimes it's art, you get the point. It's fairly chaotic.
The only hobby I have with any sort of consistency is my guitar. I'm a pretty good rhythm guitarist and can comfortably fiddle aroundthe fretboard a bit, but I haven't the goods to be a lead quite yet. That's okay with me, the rhythm part always seems a bit sexier to me anyway.
Forgot to answer the second part of the question
I do it because it's relaxing. Bad day at work? Do a little baking and all is well. Feeling a little blue? Pick up the guitar and beat it back or better yet, give it form and belt it out.