I feel like (or at least in the past) I'm in the same boat at times my dude, you are not alone. The best thing I can say is to just hang in there, as you just never know what can transpire in life, and hanging around to find out what sorts of adventures and unanticipated opportunities await is a lot more fun and exciting than just quitting and knowing for sure where and how it ends. Even if things don't quite go as planned, you don't know until you try.
Find something, anything, that makes you happy and motivated, and strive for that. Work on both physical and mental fitness, eat healthy, these sorts of things can make for a happier, stronger, and more healthy mind. You don't have to see the whole picture right now, and frankly you shouldn't b/c that would be overwhelming. Just go one step at a time and one thing will lead to another. If nothing else, keep fighting for your loved ones, and maybe down the line you'll find it rewarding to fight for yourself too.
I assume you're a gamer being on this site, so I'd recommend checking out this vid as it looks at facing the hardships of life from a gamer's perspective. I quite like the quote "maybe god/fate/whatever put your life on hard mode, (or at least it feels that way sometimes). Well beat the game anyway."