There is plenty written and researched about happiness. A quick Google search may be all you need to learn some basic tips such as keeping a Gratitude Journal or carrying out small acts of service. Ultimately, the conclusion is that happiness is an inside job rarely associated with circumstances around us.
Harvard conducted one of the longest studies ever in researching: What makes a good life? They called it The Harvard Study of Adult Development. For 75 years they tracked the lives of a group of men by getting their medical records, interviewing them and their close relatives, drawing blood, etc, in an attempt to measure their overall well being. The conclusion was that nothing keeps someone as healthy and strong as good relationships. Isolation and loneliness is actually quite toxic for humans, as their brains go into decline faster. The upside of these results is knowing what it is we need to do for our overall well being and personal success. The downside is that many other studies have brought to light the fact that America and most western cultures have faced a crisis in loneliness. There is such a thing as feeling lonely in a crowd or even in a family.