I love this book! It's just so inspiring, it makes you want to go out there and live the best life you can
I've done something similar to the "Contentment Journal", but usually when I'm down, I'm down about something about ME, so when I was still a teen, every few entries in my journal I'd make sure to write when I was in a good mood and I'd list all the things I love about myself. And it seems so little, but even having the worst day ever and reading back on those entries makes a huge difference