Even though he's still working to achieve his goal of six-pack abs -- he feels and looks like a completely different person.

CNN: College professor goes from fat to 'Mr. Low Body Fat'

Since the time of the cavemen ("How Kill Mammoth, " "How Make Fire"), these celebrations of self-sufficiency have run the gamut of topics, from carpentry and social etiquette, to stock picking and six-pack abs.

FORBES: The How-To-Do Anything Guide