I know where you are coming from. I used to be 80kgs and am 67.5kg atm and have another 7.5kgs to lose.

Just start off by walking on the treadmill for 15mins per day (the idea is to actually do it) and slowly increase the time and speed of the treadmill as you find it easier to complete. Add some floor work (abs), squats and lunges.

Look at the Calorie King website. It is fantastic and free. It has an online food diary, tells you how many calories to eat, has an excercise diary, free meal plan etc..

Check it out..

Good luck