I know what you are going through. I too have constant pain(I have an appointment with a rumatolagist next week my doctor thinks I may have fibromyalgia), daily headaches, server migraines(I take daily medication to try to cut these down and I need to inject my self when I do get one), depression(I have been diagnosted), anxiety(I have been diagnosted), very bad insomnia(I have been on so many perscribed meds that did not help) and a few years ago I thought about ending it all.
Not much makes me happy. Most people annoy me even if they have not done anything. I try to be nice to everyone but it is hard because of the way I feel everyday. After all it is not anyone elses fault.
What keeps me going is my animals. I have two cats, three dogs and all of my snakes. When ever I have had a bad day(which is pretty much everyday) they always cheer me up.