Coming home and having mine jump on my face ALWAYS cheers me up. I love everything about a loyal dog's demeanor. Their sole desire is to make you happy, how can you not love that face?
A dog outside of Pittsburgh involved in a car accident a few months back badly broke its leg. It was recommended by the vet to put her down, or to amputate the leg. After the Rankin family refused, they nursed it back to health (after a complicated system of screws and wires held the leg back together) the dog came up huge...
A few months later a fire started around 3am one night, Hero barked awake her family quick enough for them to all escape. The house was destroyed but they all lived because of the pup. After reading this, go pet a dog and feel better.
Story source -> http://www.dailymail.co.uk/news/article-1355271/Dog-saves-family-just-months-stopped-vet-putting-down.html