Kirk Douglas clearly understood something about living a long and happy life, despite suffering a stroke and experiencing a helicopter accident in the '90s. In an article he wrote for Closer Weekly on the eve of his 100th birthday, he revealed having a purpose was his secret to a long, happy life — and for him, that meant altruism and helping others.

Douglas and his wife, Anne Buydens, founded the Douglas Foundation in 1964 with the goal of helping those "who cannot help themselves," according to the nonprofit organization's website. In the article he penned for Closer Weekly, Douglas wrote, "[My wife Anne Buydens] and I always use these happy occasions to give presents to the institutions we support through our foundation." He further shared that "giving is a selfish act ... because it makes you feel so good. I am always asked for advice on living a long and healthy life. I don't have any. I do believe, however, that we have a purpose for being here. I was spared after a helicopter crash and a stroke to do more good in the world before I leave it."

He couldn't have said nicer things about his wife, Anne. In the piece for Closer Weekly, Douglas shared that he was "lucky enough" to have found his soul mate, adding, "I believe our wonderful marriage and our nightly 'golden hour' chats have helped me survive all things."