Lots of people have this idea that not expecting things is the key to happiness. I think they've missed it; not being invested in your expectations, that is more the key! Expectations can be valuable, but getting upset when they aren't met because you care so much about things working out like you pictured … that is poison.
Being easily amused can be a sign of gratitude. But, it might be a negative quality; when you receive positive feedback for minimal effort it sets a preference for minimal effort.