"We're adding on to his life."

The kids were horsing around this afternoon (as evidenced by the squeals and howling laughter). When I asked what they were doing my oldest said, "We're adding on to his life."

Have you ever heard the adage: "Laughter adds eight years to your life"? I hadn't so I decided to do a little Googling on the topic. This is what I found:

I have the feeling it was inspiration for today's ticklefest.

By the way, statistics show that children laugh on average 400 times a day whereas adults only laugh about 17 times a day. Ouch. So here's a question to ponder:

Do we stop laughing because we grow old or grow old because we stopped laughing?