It’s the winter solstice this week, which means we have officially hit the darkest time of the year. But dark doesn’t have to mean bleak. That’s the premise of “How To Winter: Harness Your Mindset to Thrive on Cold, Dark, or Difficult Days,” a new book by Stanford-trained social psychologist Kari Leibowitz, who joins us today to share a few warming tips on how to beat the wintertime blues.