Back in 1984, Steve Ockerman was a second lieutenant in the Marine Corps, stationed at Quantico, Va., when he noticed an ad campaign for Soloflex, the resistance-based home exercise machines.

Soloflex also manufactures headers, sills and corner sections, which fit with the wall units in a modular design.The walls come in 8-, 9- or 10-foot heights and lengths ranging from 1 to 4 feet.