I exercised (weight lifting and cross trainer) until the week before my baby was born and I managed to lose all my baby weight within 6 weeks. I was also very hungry all the time as I was breastfeeding exclusively, but I think the biggest factor is what you eat. I am still breastfeeding (my daughter is 11 months old), I only started exercising (Pilates) last week and I haven't put on any weight, in fact I'm still about 4 pounds less than when I first got pregnant. So for me, it's wasn't the exercise, but my diet and breastfeeding that made the biggest difference, although taking your baby for a walk every day is a good routine to get into (and exercise is great for improving energy and a positive outlook on life).
My advice is eat healthy and drink lots of water. If you are craving sweets eat fruit with the skins on (when applicable), or have a bowl of oatmeal with raisins or other dried fruit. Eating fiber rich foods, such as 100% whole grain breads and cereals, brown and/or wild rice, is a great way to feel full and helps your body stay running properly. For salty cravings eat rold gold pretzels or low fat popcorn rather than chips or fries. Even the way you cook makes a big difference. Use a small amount of olive oil when necessary and steam or bake rather than fry fish, veggies and chicken.
I too am looking at getting pregnant again in the next few months and I think that gaining a healthy amount of weight during pregnancy really helps in getting back in shape quickly. I gained 22lbs my first pregnancy and I was able to do that by eating healthy (like described above) and eating more often throughout the day.
Good luck!