I actually feel bad when I don't ride... although other forms of exercise can help relieve that feeling, there is something special about "attacking" on a bike that is hard to duplicate anywhere else.
It's funny as I was off my bike for just over 2 years after a job change... I was just fed up with auto traffic... I can now ride off the street in certain areas and this has renewed my obsession.
It wasn't the bike that put me off, it was simply dodging traffic that burned me out.