1. Secret：秘密; 机密; 秘密的
2. couldn't help but：忍不住...禁不住...
3. Pack: 包裹; 一副; 一组;一包
The secret for long happy life
A woman walks up to an old man sitting in a chair on his porch. "I couldn't help but notice how happy you look," she said. "What's your secret for a long, happy life?" "I smoke three packs a day, drink a case of beer, eat fatty foods, and never, ever exercise," he replied. "Wow, that's amazing," she said, "How old are you?" "Twenty-six."