Calorie controlled diet and lots of walking, pushing a pram uphill is knackering
I second that!!!
I just stuck to eating 2000 calories a day and took Oscar out for lots of walks in the pram. He is now pushing 40lbs, so on the occasions when I still use the pram, the combined weight of him, his pram and changing bag is around 70lbs: that's more than half my weight! I've got myself back in shape now and am in better shape than before I fell pregnant!
I couldn't go to the gym in the early days either, I just cut out all sweets, bread and other rubbish from my diet and just made sure I went for a 2 mile walk (took me around 30-40 minutes) once everyday.