I gained weight after DD was born and couldn't shake it. First when she was about 20 months old was I in a place where I could get my head around making a real effort, and really changing things.
That's when I cut out sugar (except fruit - I eat plenty of fresh fruit as well as fruit used in cooking and baking, but sparingly, as well as honey, occasionally). It took about two months to get over the cravings (I allowed myself small amounts of sugar about once a week in the meantime, like half a sweet bun or half a biscuit - giving the other half to DH). But it means all the hidden sugar, which is quite difficult. Since then I can have something nice, occasionally.
I also started exercising in the mornings (the time that suits me the best), at home (same thing), with DD joining in. I made up an exercise program that consists of a mixture of exercises supportive for ballet (which I did when I was younger), and some yoga and pilates, and some which is just dancing around the room with DD, which I can customize for 20 min-1 hour depending on what I have. DD loves to do yoga with me, and recognizes the music for exercising! And I don't work really hard, I'm not at all a sporty person.
I lost about 15 kg in 2 or 3 months.