[4][5] He then served with the US Air Force for four years and was based at Lackland AFB, in San Antonio, Texas.

[1][6][7] Following his Air Force career, he used his GI Bill benefits to enroll in St. Mary's University at San Antonio, and later received a Bachelor's degree in Accounting.

[12] In March 2020 as the COVID-19 pandemic was spreading, his Greehey Foundation pledged financial support for those in need of relief.

[14][15][16] He serves on the Board of Trustees of St. Mary’s University in San Antonio, which named him a Distinguished Alumnus in 1986 and granted him an honorary doctorate of philosophy in 1998.

[19] In 1998, Mr. Greehey was presented with the Outstanding Philanthropist Award from the San Antonio Chapter of the National Society of Fund Raising Executives; and he was inducted into the San Antonio Business Hall of Fame by Junior Achievement.