One of them according to http://www.physorg.com/news83781789.html:
"Every night, she was to think of three good things that happened that day and analyze why they occurred. That was supposed to increase her overall happiness.
"I thought it was too simple to be effective," said Miller, 44, of Bethesda. Md. "I went to Harvard. I'm used to things being complicated."
Miller was assigned the task as homework in a master's degree program. But as a chronic worrier, she knew she could use the kind of boost the exercise was supposed to deliver.
She got it.
"The quality of my dreams has changed, I never have trouble falling asleep and I do feel happier," she said.
Results may vary, as they say in the weight-loss ads. But that exercise is one of several that have shown preliminary promise in recent research into how people can make themselves happier - not just for a day or two, but long-term. It's part of a larger body of work that challenges a long-standing skepticism about whether that's even possible."