Now you might say, great idea Jen, but easier said than done, and you wouldn't be wrong. Like I said, I'm nowhere near to having things all figured out, but I can give you these few tips: 1) When your brain is not needed for complex figuring stuff out (e.x. in the shower, washing dishes, when you're at work...just kidding), try to think of things that make you happy like the best moments of your life, 2) Actually take stock of how you are feeling (and don't just say I'm fine!) and then, if you aren't blissfully happy but actually find that you are irritated, try to figure out exactly what is annoying you and either fix it or just let it go, 3) Don't dwell on things that make you unhappy, focus on things that make you happy (which is kind of a mash-up of tips 1 and 2). Now I know that everyone has problems that make them unhappy that they need to think about in order to solve them, but make sure that you are thinking about then in term of a solution and not just revisiting the problem over and over again.
I guess to sum up I'd say, give yourself the choice between being happy and not being happy and don't just fall into a pattern of not being happy. Me, I'm gonna try to have bliss as my default. ;) Cheers.