Browsing at Barnes and Noble the other day, I came across an amazing little book called "Be Happy" by Monica Sheehan.
The delightful line drawings by Sheehan illustrate each "happy" tidbit. For example:
Have a sense of wonder
Don't lose hope
Stop being a victim
Love your work
Don't compare yourself with others
I'm keeping this book here at my desk so I can refer to it often.