Believe me if taking care of our kids was a great workout all of us moms would be in great shape without trying. I have a 2 year old who bounces off the walls with energy and I play with him all day unfortunately this doesn't burn enough calories especially when you get older. Another problem that you mentioned was sweets; you're going to replace the sweets you're eating with more sweets. Just look at the sugar content of granola bars and cookies. They're basically the same. In reality there are no bad food. You can enjoy these treats in moderation but what you should focus on is increasing your servings of fruits and veggies. Those have major fiber and nutrients that your body needs in order to lose weight. Water also plays a very important part in weightloss. Just read the other post in the forum on water.
The reason you find it harder to lose weight now that you're older is that after the age of 30 we lose about 1lb of muscle a year. Muscle is the most metabolically active, meaning it burns major calories so when you lose muscle your body burns less and less calories. I just interviewed Jorge Cruise author of 8 Minutes in the Morning and he told me the biggest mistake women trying to lose weight make is they focus on starvation diets and aerobics. He said that in order to lose weight and keep it off you need to strength train 8 minutes in the morning 6 times a week. That's it. You should still do your walking but strength training is way more important and 8 minutes is all it takes. You don't even need equipment. If you're serious about losing the weight I highly recommend his book. It's a great program for people who don't have time for fitness or who don't like fitness. The diet is very realistic and doesn't deprive you of any of your favorite foods either.
8 Minutes in the Morning
