It's a simple concept, but not always easy to implement at first. But, with just a few key strategies, you can remain upbeat and positive even when the rest of the world seems like it's sinking into worry and complaints.
That's key #1 - stop complaining. Yes, forever. Complaining is absolutely poisonous and inevitably gets you nowhere but further down. Allow yourself to state what you don't like, but in a way that helps you look forward to bringing into your life what you do want instead. For instance, repeatedly whining about an unsatisfying job is spinning yourself into a web of negativity - toxic for you and all those around you (it's catching, if they're not careful)! Instead you can say in a normal, pleasant voice, "I don't like commuting two hours since it takes me away from my family too much. I'd love a job thirty minutes away or less."
Or, if you've lost your job and want another one, don't complain about how unfair your last boss was or about the state of the economy. I guarantee that will make you bitter, anxious, depressed, or all of the above. In its place, state strongly and clearly to yourself, "I'm looking forward to my next job! It will be even better than the last."