I'm sorry to hear you're in this frame of mind. I'm 5 years with this but I am slowly getting better and feeling more and more positive as time goes on. There are still days where I get very depressed but I am learning to deal with these and life is getting better. With time you can learn to not let it affect you as much, as you live more the better things in life will take over your attention.
I had depression for years and was suicidal at one point before hppd hit. Clearing up some of these underlying issues which causes depression since hppd has made hppd easier to deal with.
Jay has imparted good advice, Live as much as you can. Life isn't always easy even for those without hppd, make changes for the better where you can. Improve your life where neccessary (as per what Jay suggested), try and force yourself to get out there and be sociable and enjoy the world, be with your loved ones, get out into the fresh air & nature.
Travelling is a good shout. I went travelling for a year around the world post hppd, met some cool people, saw some amazing sights and slept with a fair amount of women (: , loved it. Am now in training to become a teacher. life is pretty good, it has been and still is a fight though and I still have times where im very resentful of hppd. But its fight that with time, you can learn to have the upper hand in and live a decent life.
Taking good care of yourself goes without saying, exercise, diet, sleep. said a million times on here but make it a routine that you base your battle from.
There are new things cropping up that can give you a slight improvement, magnesium supplements for example that Jay stumbled upon recently and are now helping some of us. Anything to give you a 0.5% or 2% improvement, slow steps you know but they can be made.
Personaly I now have the odd beer or two as the relief I get from feeling somewhat normal and the social inclusion (everyones in the pub in the uk) outweighs the worse hangover the next day. This way hppd is affecting my life less as Im not feeling its causing me to be missing out. Am equally supportive of abstinence though as this is obviously better in terms of allowing the body to make any recovery.