Same here... I had surgery not too long ago. Doctors finally cleared me for all and any workouts/ exercises. But I feel the same as you do. I once was running 6 miles with ease, lifting weights, doing crossfit, thinking about competing in figure too. But I've been out of it so long that I just can't seem to find the drive I need to get back to the way things use to be.
I keep telling myself this is my challenge. This is happening to me because I can overcome this. I know what it takes to get back to the place I was. I can do this.
I did the RealTime 30 Day Challenge. Made it to day 3. OMG! Its scary awesome. lol!