For the most part, I believe, most people want to be happy. Being happy or in a good mood isn't always easy with work and family obligation, financial and time stresses and the like. Sometimes life can seem overwhelming. But I have found that there are somethings we can do to stay happy.
First... as often as possible keep people around you that that make you happy even if it's just a picture. Second have faith that no matter what happens... in the end it will work out and you will gain something , even if it's just some knowledge. And third stay in a state of gratitude.
My wife recently bought me the book ... The book of awesome. It is full of small examples of things in life that we sometimes overlook or take for granted, that we should be grateful for. Things like: when you are in a hurry and the cashier opens a new checkout and invites you over first. Or going to gas station and filling up the night before the prices rise. When the person you let in- in traffic actually gives you a thank you wave. When your suitcase is one of the first to hit the carousel at the airport after a long flight.
These are just a few examples of the dozens in the book. It's one of those books you can pick up after a not-so-good day and be reminded of all the things that have gone right. It's a quick and uplifting way to erase the negative of the day. It's a way of staying in a state of gratitude because the small things matter too.
If you can, I suggest picking it up, keep it handy and read one or two segments when the feeling hits you.