Fabulous by Fifty

I'm closer to 47 than 46 now and I'm the biggest/heaviest I've ever been in my life, including 3 pregnancies. Knee pain started recently and I know it is the 90 extra pounds I'm carrying everywhere. Next December I'm taking my grown daughters on a cruise and if we do hiking or sightseeing excursions, I don't want to be in pain and out of breath the whole time. I think I can lose the weight in a year, but I need a continued dedication to working out. I'd like to be my "best me ever" by my 50th birthday.