In order to feel happier, often we need to work on ourselves and our state of mind. When stressors come up, or something bad happens, we can forget we ever felt happy and negativity can begin to take over. When this becomes pervasive, all areas of life can suffer. Working to increase happiness really can enhance overall wellbeing, including perception of personal effectiveness toward meeting goals.
Here are some tips from Mindful magazine to enhance your level of happiness! I especially like the idea of keeping track of your joys. I often recommend a positivity journal to remind yourself of the good things when the hard things set in.