"I was born in 1960, which is pretty much when, as a culture, we started exercising. I was interested in the way my own life overlaid that cultural history." Cartoonist and memoirist Alison Bechdel talks with Zibby about her latest book, The Secret to Superhuman Strength, and the ways in which exercising has both reflected and shaped the stages of her life, from adopting new routines based on cultural trends to analyzing how exercise intersects with mortality.