Guren was born in Cleveland, Ohio, on October 25, 1924. He graduated from Cleveland Heights High School in 1942 and Western Reserve University (WRU) two years later. Upon graduation from WRU, he was admitted to Harvard Law School where he became editor of the Harvard Law Review. During his second year at Harvard, Guren was drafted by the U.S. Army and, after training, was promoted to sergeant and assigned to the Pentagon in Washington, DC. Guren returned to Harvard in 1947 and graduated in 1948. He then returned to Cleveland and joined the law practice of his uncle, Henry S. Gottfried, and that fall, at age 23, he became a partner in the firm Gottfried, Ginsberg, and Guren. The firm grew, and by 1983 included 68 lawyers and 70 non-lawyers, with offices in Cleveland, Columbus, and Miami. 

Guren’s other business ownership interests included Thistledown Raceway, New York Yankees, Cleveland Browns, and Chicago Bulls. In addition, he also had ownership in Cleveland Stadium and a horse breeding farm in Ocala, Florida. 

The Towing Company spurred many other marine-related businesses, including Admiral Towing and Barge Company, a government tug contractor; Soo Linehandling Services, which handles dock lines ashore for ships transiting through the locks at Sault Ste Marie, Michigan; Runyan Shipyard, Inc., a Pensacola, FL ship repair facility; Tugz International LLC, a tugboat chartering business; Puerto Rico Towing & Barge Co., a harbor towing operation in San Juan, Puerto Rico; and several others. 

Guren passed away peacefully in Jackson Hole, Wyoming, on August 16, 2024. He was 99-years-old.