John Zug was born in Carlisle, Pennsylvania on March 28, 1818. Little is known of his childhood except that he began to study Latin in 1830. These studies allowed him to enter Dickinson College on September 10, 1834 as a sophomore. During his years at Dickinson College, Zug was an active member of the Union Philosophical Society, giving an address at the society's 47th Anniversary Celebration held July 4, 1836. His oratory skills appear to have been well known in both the community and the College, as he addressed several college and local groups on special occasions throughout his school career. Zug also claimed to have become "religious" on December 6, 1835. What type of event or conversion took place is neither known nor recorded, but presumably his affiliation with the Methodist Church began around that time. Zug graduated from Dickinson with the highest honors on July 20, 1837, and addressed his graduating class at Commencement. He enrolled in the law school on October 3, 1837 and was admitted to the Carlisle Bar on November 9, 1839. While at the law school, he was active in the Pennsylvania Colonial Society, serving as an agent from July 26 to November 26, 1838.
Zug accepted a position as teacher at the Dickinson Grammar School in 1839, and served as principal from February 25 to July 10, 1840. He then moved to Baltimore where he founded his own grammar school, the Light Street Institute; classes began in 1840. The institute focused on a classical education comprised of the classical texts, mathematics, Greek and Latin. During this time Zug was also active in the temperance movement in Baltimore, delivering speeches on behalf of the Washington Temperance Society of Baltimore. He drafted a history of the society in 1842, and although he submitted it for publication, it was ultimately rejected.
John Zug relinquished his duties at the Light Street Institute to John H. Dashiell, and returned to Carlisle to practice law. He died of a pulmonary complaint on September 5, 1843 at the age of 25. He was survived by his wife Margaret Ann and their infant child.