When people ask me what I do, strangers on a plane, perhaps, I tell them that I think. Thinking is excellent exercise, as much as swimming or jogging.

Advertising Disclosure: Please note that many links to retailers are affiliate links, which yields a commission for us. allauthor.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon sites.