Some psychologists ask patients to imagine or picture what they want in their lives - getting a new job, meeting someone special, having a child - in order to create a mental state that visualizes what is achievable.

"If you experience visualization with your eyes closed, your mind doesn't know if it's real or unreal," says Mary Ann Troiani, co-author of Spontaneous Optimism. "Neuropsychological ways makes them feel as though they have it and tricks the mind into thinking they have [what they are visualizing] now. It makes them more confident about it."

  
There is much research in PubMed behind visualization and emotional changes brought on by optimism, as it has been shown that positive thoughts have an impact on the brain's biochemistry.

Related

1. Here is a Google scholar search for happiness research.

2. Here is a PubMed search for happiness

3. The medical subject heading [MeSH] 'Happiness' is defined as:

"A highly pleasant emotion characterized by outward manifestations of gratification; joy."

Sounds good, doesn't it?