I read in one of Wayne Dyer's books about how, if you just can't leave the job you're in, to learn to at least be happy in it, but can't remember which one it was.
One of his suggestions, and others say as well, if you really hate your job, at least find something you love to do on a part time basis and maybe it will grow to the point where you can give up the job you hate.
Spending 40+ hours a week doing something you really hate is a spirit killer. However, if it's just a matter of wishing you were walking on the beach on some island as opposed to working at all, maybe you just need to find some fulfillment in other areas of your life.