Greive's hobbies and interest include: sky-diving, desert racing, scuba diving, wildlife, adventure travel, art, cooking, science, and reading. Greive has said his favorite authors include Joseph Heller, Douglas Adams, and Gerald Durrell, and his favorite painter is Philip Guston. Other historical figures Greive admires include: Richard Feynman, Jacques Cousteau, Howard Carter, Robert Goddard, Marie Curie, Yuri Gagarin, Erwin Rommel, David Lynch and David Sterling. Greive has been quoted as saying his favorite fictional character is "The lace-making, latently heroic Beaver from Lewis Carroll's Hunting of the Snark."