Giving back seems to be the secrete sauce of happiness to a lot of happy people out there. When you think about the smiling happiest people you've met they're usually "volunteers" doing something for the community. This could be volunteering for the annual Thanksgiving day turkey meal for impoverished families and individuals. This could be hosting a fundraiser for a great cause to fight cancer to provide food, water and aid to impoverished regions.
Regardless of what an individual is giving back to, the net effects of giving seems to be very net positive in terms of life outlook, immediate gratification, and overall well being.
A good example of this has been over the past few years, I've run two Charity:Water (http://www.charitywater.org/) campaigns during my birthday to provide clean and free access to drinking water in underdeveloped regions of the world. Over the two campaigns we've raised over $2500 that has gone to two individual sites providing clean drinking water for an entire village. Imagine that what you spend on monthly rent in NYC, SF, and SEA could do for an entire village for years to come.
Now I'm not saying we should all give all of our money away all the time. Instead when you are feeling a bit low, need a pick me up, or feel like you haven't done too much recently to positively impact the world around you, try some giving back. It'll do you a whole lot of mental well being and probably you will impact someone else's life in a big big way.
Here are some links to research on the positive effects of giving:
https://www.psychologytoday.com/blog/the-compass-pleasure/201108/is-your-brain-charitable-giving
http://psychcentral.com/blog/archives/2013/12/22/how-giving-makes-us-happy/
http://www.hbs.edu/faculty/Publication%20Files/10-012.pdf
*Please note all essays are usually written as is, as a work in progress, based on thoughts I have. Opinions, ideas, and statements are mine and do not represent fact and should be filtered based on your own judgement.