There is someone you want to communicate something to, and for some reason you cannot do it directly. So you write them a letter. Because it's a letter you write it exactly like it is, honestly, without holding back.
And then you realize that writing it made a big difference. It happens even before you send the letter (if you do at all).
Turns out, the same can happen when you write a letter to Joy! Whether Joy is already a big part of your life, or not so much, writing to Joy can connect you with it deeper and eventually lead you to feeling more Joy every day, regardless of your circumstances.