I don't recommend Zyprexa. My prescibers oversold the benefits and understated the negative side effects. I was on a low dose (7.5mg/day) for almost 10 years in which I gained 60 lbs above my optimal weight of around 210. I also pushed pre-diabetes levels for blood glucose. Also had mild paranoia/obsessive-compulsive condition: always excessively worried about very minor things. I'd had enough last year when I started developing twitches and became afraid of developing Tardive Dyskinesia (also a greater risk of contracting than I was told). I talked my shrink into taking me off of it. Weaned off over a period of about 4 months. Process was not too bad until stopping entirely, then became unpleasant: anxiety/irritability (hard on the wife), extreme lethargy for a week or so, tics actually worsened for about a month, and developed a mildly annoying itch-like condition that persists to this day.
I have not had one day of depression since I quit it and the paranoia and worries have disappeared. I'm still on 200mg/day of Lamictal ( lamotrigine) which I also plan to take a stab at quitting. If I were you, I'd do some research on my own: lots of well-trusted sources available online (NIH, JohnsHopkins, Cleveland Clinic, Mayo, of course).

Good luck!