I'm similar to the others. And remember it tooth 10months to put on that weight - it's OK to take that long to get it off.

I either drag my tired bottom out of bed a bit earilier for some yoga (it's a bit quieter), I have a cross trainer that I can hop on while they're amusing them selves.
Have you got a sling? When DS was little (hell I still do it now he's not) I put him in the sling (he goes on the back as opposed to the front now), DD in the pram and go for a walk - the extra weight burns extra cals (well in my mind it does lol).
We also got a bike trailer that converts to a pram. DD calls it the big red bus, and they both fit in it. However my DS is a lot bigger than your DD.

I make a conscious effort to move more. For eg if DD's talking and I can't hear her I walk over to her instead of asking her to speak louder. Might sound silly but all the steps add up.