Perfectly legitimate and reasonable question! I just had a JW tell me that an atheist's world is a dark, dismal, dreary one. I told him I've never heard an atheist comment to that effect, had he? He never answered.
I live to be happy. That's really about it.
If I help other people be happy, that makes me happy. If I make people sad, it hurts me, so I avoid it.
If I like eating certain foods, I do. Often. I avoid doing things I don't like doing, unless doing them makes someone else happy, which makes me happy.
I give to beggars and charities. I prefer personal giving, but giving to an impersonal charity makes me happy, too.
Having removed the supernatural side of my life, I don't sense that I'm missing anything, living worse, enjoying life less, or less hopeful about the future. If anything, I feel much better overall. (But in fairness, I only have my JW days to compare to, so take the observation for what it's worth.)
I dream of going on vacations to beautiful, exotic places. Might happen someday, and I'll enjoy it. Or not, and the time I spent dreaming about it will have been fun, too.
One day I'll go to sleep (just like I do every night) and there won't be a next day for me. I won't even know I'm gone.
Dave of the "loving life" class