I am sorry for your recent medical challenges. I am 59 and a two-time breast cancer survivor who, like you, was used to nearly-daily gym workouts. Like you as well, I had an oopherectomy almost two and a half years ago as well. I found that doing small workouts kept me focused on physical health and helped me believe that returning to normal physical activity would not be quite so challenging if I did just a little in the gym. Try doing just a few leg lifts or arm curls [if you have been cleared by your doctor to do so], or get on the treadmill and elliptical for 10 minutes rather than 30 or 40. I wish you the best of luck.