Kristen Johnston, the towering comedic actress best known for her role on "3rd Rock from the Sun," may bring the laughs on TV Land's "The Exes," but in reality, the star has been battling some serious personal issues. Johnston recently penned a powerfully honest memoir, "Guts," in which she writes about her miserable school years, her rise to fame and, most stunningly, her addictions to drugs and alcohol.