Its totally pathetic. I just started trying to do one of the yoga DVDs I used to do pre-baby and I could barely even bend!
DS is 5.5 months old. Before I got pregnant I was doing a combination of yoga and Pilates classes, swimming and calorie counting. I was really quite overweight but it was coming off - 12.5 stone at 5 feet tall 
but now, post baby, I am 14.5 stone and utterly miserable (thanks to SPD that meant I could barely move in pregnancy).
DS was a Velcro baby who has only started sleeping by himself, without being held, this past week. So I thought I'd start getting on with it and its so bad that I can barely exercise :(
So I'm on a healthy eating path that I can stick to as long as I don't buy snacks - I don't miss them if they're not there! I walk everywhere with DS in a sling but have planar fascitis from pregnancy that means I can't do too much of this. Ironically losing weight will help make it better...
I have ordered Davina's 15 minute fitness (thinking I may be able to stretch to that long) and 30 day shred. Planning to start doing every other day and build up from there...
But when I think about how much I have to lose it brings me to tears as it seems totally insurmountable. I'm 14.5 stone. My happy weight, which I haven't been in years, is 8.5 stone, though I'd be satisfied with 9.5. 5 stone, dear god :( how am I ever going to manage that??
Someone please tell me I can do it and it will get better. I can't go on like this but I feel like I can't fix it either... :(