That would be 50 pounds in 84 days or approximately 0.6 pounds per day. One pound of body fat contains around 3500 calories so that would be burning approximately 2100 calories more each day than you consume. That sounds like a very aggressive plan and will require a lot of discipline. Most people working on their own (without a trainer) have more success at keeping the weight off long term when losing only 1 to 2 pounds per week. I know that stretching it out over six months to a year does not sound as appealing, but the crash diet weight loss is what causes a lot of people to yo-yo up and down. But consider that at the very doable 2 pound per week loss rate you can be half way to your weight goal at the 12 week mark. The keys are diet, exercise, discipline, lots of water, adequate rest, weigh on an accurate scale (I weigh myself every morning before breakfast for consistency). For motivation many people find it helpful to put a photo of yourself at your desired weight on the refrigerator. Then make sure that you get some clothes to show off your accomplishment. Best of luck to you on whatever approach you choose.