Greg Johnson is director of Resources For Life, an outreach and public interest organization based in Iowa City, and president of the Small House Society. He has spent more than eight years living in a home with less than 400 square feet, six of them in a “mobile hermitage” of 140 square feet. He also wrote a book about his tiny house living: “Put Your Life On A Diet: Lessons Learned From Living in 140 Square Feet.”