The secret of health for both mind and body is not to mourn for the past, worry about the future, or anticipate troubles, but to live in the present moment wisely and earnestly.
This definitely holds true for me... though sometimes it does take more effort than it should. Specially if you're not used to NOT thinking about the future or anticipating troubles ...
But, this is good advice.
I believe it's a great way to beat stress, too! :)