As reader’s of this blog or my parenting book know, the science of positive psychology has a great deal to offer us regarding how to be happy. One of my all time favorite strategies is to write a gratitude letter. Below are the stops and a link to a brief video where I describe the strategy.
Step #1: Identify a person towards whom you feel a significant amount of unexpressed gratitude. This might be a person who knows about some of the gratitude you feel but not all of it. This gratitude can be recent or ancient. You can also rotate writing a gratitude letter within a family: week #1 is moms turn, then eldest son’s, then dad’s, etc. Then everyone writes a gratitude letter for the person whose turn it is.
Step #2: Hand write a legible letter of about 300 words. Don’t worry about a precise word count, just land somewhere in that ballpark. (The handwritten nature of the letter produces a more personal feel and indicates more effort on your part.)
Step #3: Schedule a meeting with the person, but don’t tell her or him about your letter. The surprise tends to make the experience more powerful.
Step #4: Read your letter to the person. Don’t chicken out and hand it over for the person to read as that stands to significantly weaken the experience. Don’t worry if you get misty or cry as such usually adds meaning for the other person; plus you probably won’t be the only one.
Step #5: Give your letter to the person.
Here is a video where I briefly describe gratitude 
letters (click on the image):
I’ve done this myself, had families do it in my office and asked my students to do it. I find that just about everyone (myself included) is surprised by how powerful of an emotional experience it proves to be. The research also suggests that the writer of the letter can experience a bump in happiness for a few weeks afterwards. So, give it a try it and see how much power you have to manufacture happiness in your life and the life of another.
Dr. David Palmiter's Blog for Hectic Parents 