Choose to be optimistic; it feels better.

You can see more of Molly Hahn's beautiful "Buddha Doodles" at her website, and she also has a series of books (including a Kindle book) at Amazon.

The quote is: Choose to be optimistic; it feels better. Dalai Lama XIV

You will see this quote all over the Internet; I don't have a specific source for it... but it sounds like the Dalai Lama! You can find out more about Tenzin Gyatso (the 14th Dalai Lama) at Wikipedia, and you can find more quotes from the Dalai Lama at Wikiquote.