[2] The family later moved to Brownsville, Brooklyn where the senior Greenstein began his shows as a miniature Samson in vaudeville and Yiddish theaters.
During World War II, he joined the United States Army Air Forces and was assigned a mechanic MOS.
During that time, his father was touring the country entertaining troops and did shows to raise money for war bonds.
Inspired by his father, the younger Greenstein decided to start an act of his own to entertain the troops at the various bases he was stationed in by bending bars, breaking chains, and pulling passenger-filled cars with his hair or his teeth.
[2] Living his later years in Rockaway, Queens, New York, Greenstein was a strength athlete by profession, known as the Mighty Atom Jr.