I just went over some of my fitness goals for 2009.  If I can stick to an actually-achievable goal schedule, the difference I could make in just four months is pretty amazing.  It will take a LOT of iron slung about, and a LOT of protein.  But – I did it in 2006, and I’ve managed to retain a lot of that muscle mass, even if a fair amount of bodyfat found its way back on.  We’ll see how it goes.
Try not.  Do or do not.  There is no try.