I got that way a long time ago. I read something in a novel about a dog chasing a cat, the author remarked "I envied that dog's enthusiasm" - just how I felt. It was constant, I just couldn't feel arsed to try anything, couldn't enjoy a single piece of entertainment. Even when good stuff happened to me, like passing my driving test, I never felt "wow!" about it, just vaguely glad of a good result to prop me up for a couple more days.
It's a lot better now. I guess bad experiences just made me that way for a while. My life has been stable for a good few years now. There's a condition called flattened emotions where you repress the negative stuff that's too heavy to bear, but it's rather like an anasthetic, it makes you numb to everything, even the positive stuff. The classical solution is to talk out the bad memories with a skilled, supportive listener. Releasing it to yourself can do some good, but it's better when somebody else knows. I never really released much through counselling, but over the years I've begun to let out a lot of the bad stuff I went through. Just answering the questions on Aspie topics that provoke memories has been quite cathartic.
But it's unwise to do too much at once. When you re-live the bad from the past, the emotions it stirs up can continue, and as emotions are blurred things to me, I've sometimes overdone it and ended up in a seriously wacky mood.
I always get a lift from knowing I'm getting something done. Clever achievements at work and at home have often been the only thing that has kept me going. I'd almost stopped bothering with people at one stage, but found I needed to know that I was at least doing one thing, anything, to foster human contact. There had to be some kind of hope for better days.
The worst times were when my girlfriend lived 70 miles away, I could cope with being alone during the week but after returning from weekend visits on Sunday afternoons, it was like a dark mist would fall over me until the following morning. It had a dream-like quality, & very hard to describe. I used to dread it, and tried changing aspects of the journey home and of my routine on arriving back, in the hope of avoiding some unknown trigger. Sometimes that seemed to help.