I did not lose that much, but I did lose 30 in 6 months and have kept it off for 6 months now. I want to second (or third) the recommendation for diet apps. In my case, I used My Fitness Pal. But I'm sure others are just as good. I figured out how much I should weigh using a BMI calculator and entered that I wanted to lose 1 lb a week. In the beginning, I lost more lilke 1.5 or 2. It was VERY hard at first- I felt very hungry. But, it got better. I think counting calories is absolutely the way to go. Excerise is great for your health, but I don't think you will lose weight unless you count the calories, unfortunately. It also helped me to only eat things that I found very tasty, rather than a huge portion of meh foods. I did not particularly reward myself, other than doing a little dance of joy each time the scale moved! Also, I needed several new wardrobes as my weight went down, so I inadvertently rewarded myself with new clothing. Good luck!