Trying to make peace with my situation

I'm not going to go into too many details as there's too much to explain and things to get sidetracked by but, suffice it to say that my situation is not what people would call 'normal' for my age and society would expect 'more' of me, yet it's not as simple as outsiders would think/claim it would be for them.
There are certain obstacles, both mentally and physically, that has had me in a sort of limbo for the past couple of years and to be honest is not something I see changing. On the one hand, I feel like I am resigned to it, I will never have more than I have now. On the other hand, it scares me. Am I really living, what is happiness, what is satisfaction with one's life.
I haven't worked in some time, I don't have much of an interest in anything and I don't know of anything new I would have an interest in, I'm not very social as I get anxiety from socializing, yet I fear the day when I might truly be alone and, unless I meet an untimely end, that day will happen.
Often things I do have an interest in falls by the wayside due to a lack of energy or I get halfway through, just to lose interest and when I want to revisit it I feel I have to start over, making it so I don't really have a stable focus point in my life. In fact, when I do have a focus point, I get hyper-focused to the detriment of all else.
I have at times wondered about people who have very limited to no control over their lives, paraplegics, the blind. How do you find satisfaction in your life when all you can do is move your head or can only partially experience the world around you.
I am far from being paraplegic or blind though I do have some, comparatively small, difficulties. How do I find satisfaction and happiness, given my situation. How do I even know whether what I have is enough when my emotions are driven by depression. I have somewhat accepted that the depression, et al, is being handled as best it can and that this is as good as it's going to get. I won't have clarity and stability the way that I have had glimpses of from time to time, my life will forever be ruled by the subtle undertones of depression, anxiety and limitations of physical ability.
These thoughts in and of themselves is enough to drive one to despair and looking for ways 'out'.
How does one find meaning, in the mundane. How does one find happiness in the mere fact that you are alive.