Karen,
Way to go!!! I know how hard this was for you. I lost 65 lbs. a while back and it is a DAILY STRUGGLE!!!!! I have kept my weight off for almost two years now. The most important thing, in my opinion, is to do weight bearing exercise, along with areobics. When you build muscle, it burns calories even when you sleep. I still, very much, have to eat low fat, low calories. Drinking the gallon of water per day is very difficult for me as I drive a school bus and I can't go to the bathroom whenever I want, but that is a big part of losing the weight and keeping it off.
Now, the fun part is CLOTHES. I have never had so much fun with clothes!!! No more HUGE BUTT!!! YAHHHHHHHH!!!!!!! I am sure your life is changing drastically for the good! Enjoy it and be proud of turning "50" it is the new 30. I'll bet you can actually get on your horse without a mounting block. That is what happened to me. Now I ride often.
YOU ARE A WINNER!!!!!