I'm 5'10 and 138 lbs and lost 40 lbs over the course of 3 years. I'm also 52 and that makes is doubly hard not to gain weight when you are menopausal. I found two things that are essential:

1) Develop an eating plan that you like and fits your lifestyle. If you look at this as a "diet" you are going to do until you lose the weight, you won't succeed in the long run. Only by eating food that you enjoy and are happy with can you make this a way of life. That might mean taking the foods you like best and "de-carbing" them, eating low or zero carb bread products or whatever it takes to create a menu that you can live with.

2) Aerobic exercise is, for me, essential to maintaining weight and health as well. I try to do things that I enjoy and are fun. Again, if all you do is a DVD or go to the gym for short-term results, you're not likely to stick with it. Having some fun activity like tennis or swimming that you enjoy on a regular basis is the key to long-term exercise success.

In short, the key to success is to make your life enjoyable while maintaining healthy exercise and eating habits.