I hear you on the tired of being fat! My pregnancy was pretty easy. I gained about 50 lbs - which on a 5'1" gal is noticable. The delivery was the killer for me. 18 hours of labor and they had to run me over to do a C-section. I lost almost 3 times the amt of blood that I was supposed to and I had a reaction to the meds and stopped breathing so I was in recovery for a while. I just got the ok to start working out etc a couple of months ago.
Anyways, I am starting off pretty easy on the workout. I do M-W-F 45 minutes on my stationary bike at level 3, then 15 minutes of alternating squats and lunges.That usually comes out to 3 sets of 12 each by the time I hit the 15 minute mark. I am rather clumsy so I dont go very fast :) On T-Th-Sat I do all upper body: push ups and weights. But to get rid of my middle, I have been doing sit ups with every workout. I find that doing 50 before I start and 50 after is great - that way my stomach doesnt get so sore all at once and I have more energy to do all of them and not cheat.
I used to be a runner - I loved running. But since that is not an option for me now, I find that what I am doing so far is fun and easy to stick to. If only the diet were that easy! I had an ice cream craving last night that come out of left field. The temptations! Hopefully it will get easier with time.
Take care and good luck!!