"Anne of Green Gables" and its sequels. I love the simple, every-day stories LM Montgomery writes and her philosophy of life that shines through. The first reminds me of the way I grew up and the second has often inspired me. I also love the way she sees beauty in everything, and how she conveys that in her prose. These are the books I turn to when I am depressed or stressed or just fed up with life in general :-)
Also recommended in this reply