Tony has a good point about maintaining achievable expectations. However, I think one of the things that gets glossed over is that there is a difference between "resting" and "wallowing", where you're continuously worrying about things that have happened, will happen or -as it seems in your case- aren't happening. In the event of the latter, there's about two schools of thought you're going to come across when it comes to what you can do about it:
1. Those whose who prefer mindfulness, accepting and understanding that what they feel is transitory, that the feeling is just a sensation and will pass naturally, thereby avoiding obsession which would only prolong the issue.
2. Those who prefer a more active route, identifying issues that bother them, and taking action to rectify them. Frequently this is paired with motivational interviewing where you don't just identify problems, but also goals that you want to achieve and steps to get you there. Obviously this is a lot more varied; in some cases, this means going to therapy, abstinence (smoking/drinking etc.), volunteering, starting a new hobby, or simply going out more. Note that this is about taking the right steps, not just any steps. And as always, determining what's right and wrong is hell of a lot more difficult than it seems. Quitting a stressful job may be a good thing, but a) that's not always possible, and b) you're likely to lose the support network you have there amidst your friends and coworkers, not to mention the obvious problems that unemployment brings. That's not to say it's never the right thing to do, I'm simply using it to illustrate that this is a complex issue.
Both schools have their merits, and you'll find that both are being used in professional therapy today (e.g. mindfulness/meditation therapy and behavioural activation, respectively), with proven results. It should be mentioned that they aren't mutually exclusive, and there's no reason not to apply both since they cover each other's weaknesses. It's just that some people respond more to one than the other. It really depends on your personal situation.
There's plenty of great resources on mindfulness online if that's what you're interested in. Behavioural activation and motivational interviewing is a bit trickier, and usually means visiting a professional (therapist, career counsellor, etc.). You CAN do it on your own, but I would advise against it, since you'll want an objective third person's perspective.
