When she was 20 or 30 years old, how did Gwyneth Paltrow see what she'd be doing at age 50? "I don't think I thought about it," she replied. "I thought, you know, 50 is, like, you're dead at that point!" Though clearly far from dead, Paltrow, who will indeed turn 50 this week, is already well into a second life. She's founder and CEO of the lifestyle brand Goop. It comprises a website, TV shows, and lots of products aimed at making you feel and look good. The Goop flagship store is in Santa Monica, Calif., where Paltrow was...