I have a long standing brain injury and had to have surgery for a problem it was causing a few years ago. I am super active, super competative, very driven and energetic yet the same thing happened to me, I couldn't be bothered to do anything, didn't care how I looked, what I wore, what I ate (or didn't), how it affected anyone else- it was depression pure and simple brought on by being incapacitated. Took a while to get back to normal and I did it by imagining my whole life was a job with set things I had to do at certian times, so I would wake up at 8.00, make breakfast, wash up, go out and walk the dog, come home read two chapters of a book, make lunch, do some work,write, go running, chekc on my business's (sons were running them whilst I was ill), go home shower, go out to eat, do a quiz maybe go clubbing- and I had to FORCE myself to do things everyday otherwise I'd just slob on the sofa- but eventually my normal energy and interest returned, but it took a hell of a long time.