I don't want my baby to grow up fat

my baby girl is almost 5 months old now. i gained about 35 pounds during my pregnancy, and even though i lost a lot of it i'm now almost the weight i was when i had her. when it was warm, i took her for a 3 mile walk every day. now that its been colder, i dont want to get off my butt and do anything at all. ive been using all these excuses, saying that i cant do anything because i have to watch cailyn and i have no time to exercise, and also that stress is the reason i overeat. ive realized that cailyn isnt my reason for being fat, she is my reason for getting healthy and fit. i dont ever want her to see me binge and think that its ok to do that. i want her to know that it can be fun to exercise, and the way to teach her that is to lead by example. it isnt going to be as easy as i'm telling myself it will be, its going to take a lot of work, but i have to do this for my daughter and myself.