Concerned for my health, how do I lose weight the smart and healthy way?!

Concerned for my health, how do I lose weight the smart and healthy way?

I stepped on the scale today, 135lbs! That is at least 15lbs over! I'm 5ft even. Before my son 6yrs ago, I weighed 115lbs, then gained 40lbs during the pregnancy and 6yrs later I still haven't lost it all.
I've been walking WAY more than usual lately, as much as I can and I drink lots of water. I've also stayed away from fried food and junk food. I LOVE baked mac and cheese. It's the one thing I have to have. But I'm willing to stop seeing as how I may put my health at risk.

I've gone on diets before, dropped all the way to 125 from 140 in 2mths while working in retail but then gained it all right back. It's harder to lose weight since I sit at a desk now. However, once I'm set on something, I definitely follow through. I just want to make sure I KEEP it that way this time.

Any ideas on what I can do to bring my weight down? I work FT at a health insurance office so I sit for at least 6hrs a day, 5 days a week while at work.

Thanks in advance! :-)

Here are a few tips:

1. Eat TONS of fruits and veggies. Have fruit and yogurt for breakfast. Make all your snacks fruits and veggies. Have small portions of meat and starch for dinner and have as many veggies as you want (not too much butter). The average American diet is way short of fresh food. P.S. Don't overcook them, they lose nutrients that way and also lose much in the way of taste.

2. Decide in the morning what you will eat that day (or the night before). This will stop you for eating things you shouldn't/don't want to. This isn't as strict as it sounds. You can plan desserts or snacks or the foods you love into your meal.

3. Bring your snacks and lunch with you to work. Do not eat anything you didn't bring. If you pack the proper food, you shouldn't be hungry and anything else you eat is just extra calories that end up on your butt.

4. Learn to love the food that's good for you. Start thinking of healthy food as a gift you are giving your body.

5. Do not make yourself go hungry. You don't have to be hungry to lose weight. You just have to eat foods that fill you up but don't have the extra calories (fruits and veggies, yogurt, fish, chicken).

6. Save those special foods that you love but are high in fat and calories for special occasions. Have them once or twice a month. If you have to have them more often, cut the portion size down.

7. If you aren't willing to make changes to your diet, the only way to lose weight is to exercise.

8. If you are a late night eater, cut yourself off after dinner.

9. This may be the most important: HEALTHY FOOD DOES NOT HAVE TO TASTE LIKE CRAP. Learn to use herbs and spices. Get a really good cookbook that has low fat and calorie but high in flavor meals.

I hope some of these help. The real key to being healthy is to want to be healthy and to enjoy it. Eating well and exercising is not some price you have to pay to be thin, it is a great gift you are giving yourself.