I'm 56 and have had life long depression. I've had terrible low points and wonderful high points. If I had checked out when I was young, I would have missed out on the best things life has to offer. Yes, most has been dull, boring and lonely, but the happy times make it all worth while.
Hang in there. Find a purpose. I know it's hard when you are suffering, but looking forward and having hope is important. Fixing yourself is done in small steps, a day at a time. You can do it.
Every day you wake up is a new opportunity for something good to happen!