Alice Herz-Sommer, the oldest living Holocaust survivor, turns 107 today. When asked her secret to a long life, she answered:
"In a word: optimism. I look at the good. When you are relaxed, your body is always relaxed. When you are pessimistic, your body behaves in an unnatural way. It is up to us whether we look at the good or the bad. When you are nice to others, they are nice to you. When you give, you receive."
For more info about her, here's a biographical web-page:
Alice's story.