Everyone loves a winner! And if you're having fun at work, you'll look like you've already won. A positive attitude is attractive, and people respond to excitement and enthusiasm. If you can find a way to enjoy your work, you'll discover good things start to happen.
Of course, I also once knew an MBA who shared his best tip for having a successful career. "Always be looking for a better job offer." He always had an up-to-date version of his resume available on the top job-searching sites. He enjoyed the act of looking for a job, and talking about his skills in new job interviews as they came up. Eventually, over the years, his resume would get discovered by a better employer, who would offer him even more money if he switched to their company. (Often he'd end up doing the same kind of work - but he'd be doing it for a lot more money!)
It's always exciting to earn money, but it's even more exciting if it's doing something you enjoy. If nothing else, you can enjoy spending all the money that you've earned after work - on weeknights and weekends! But it's even better if you can enjoy the work itself, so you're then enjoying yourself seven days a week. Sometimes it's as simple as changing your attitude while you're at work- but in other cases, you might want to try changing your job!
I learned a valuable lesson from my MBA friend. Because he was "always looking," he always felt like he was the one in charge of his career's direction. If there was a difficult situation at work, he always knew that he had other options available. He felt confident enough to speak honestly to his managers about what he wanted from his position and his workplace environment. This was the second thing I learned about how to make work more enjoyable: do what you can to take charge of your own work experience.
Some people adjust little things, like bringing in photographs of their loved ones or a calendar with pictures of tropical beaches. I once found my job satisfaction increased dramatically when I bought an mp3 player - because then while I was doing the company's work, I was also spending the entire day listening to my favorite songs! And it sometimes helps if you make an effort to find a few friends at work. Then you can mix in a little socializing during your lunch hour, and work won't seem as isolated or alienating.
Someone once told me the key to having fun at work was to ask a lot of questions, because "The more you know, the more fun you can have." And it's more interesting to watch the day-to-day flow of the business if you understand what's a big, exciting development - and what situations can be dangerous and depressing. You may even spot an opportunity for a new project where you can volunteer. Sometimes the key to being happier at work is, surprisingly, to just take on more responsibilities that you'll find more interesting and challenging!