Prozac question!

Anyone on Prozac or another depression medication that has ever felt like they can't concentrate? I had some problems with this before my meds, but recently I've noticed its interfering a lot with my work. I will be in an overall great mood and get to work and my brain is constantly jumping tasks and I have at least three to do lists and a post it note graveyard on my desk to keep track of the things my brain remembers it needs to take care of! Then my good mood is spoiled by being frustrated with myself! Occassionally I will literally leave my office and walk around the block to get some of my energy out... Anyone have similar feelings?