Now, I can't give you actual advice, if this is something that's constantly bothering you, you might want to speak to a therapist. What I can offer is my perspective - however, you might want to know beforehand that I'm not chronically ill. I had medical issues which weighed on me quite a bit, but those turned out to be resolvable after about 2 years.
I don't think live has any grand purpose and you'll never be content if you try to chase one either. There is no point in waiting for something that may never come. The best thing you can do is to find things you enjoy and maximize whatever you can get out of live. Try lots of different things within your means, visit places and meet new people. The worst thing you can do, from personal experience, is to repeat the same things every day. Your days blur together and there is no meaning to be found in them.