Mary Zettel began her career with Seneca College in 1977-78, where she worked above and beyond the call of duty trying to help further develop OCAA athletes, sports and the administrative systems that support them.

During her years at Seneca, Zettel introduced many innovative programs that helped to enhance the effectiveness of sport administration. In 1985-86, she began her lengthy term as vice president on the OCAA Executive. She also found time to serve as soccer convenor and sit on various OCAA committees, while playing an essential role in hosting OCAA and CCAA championships.

Mary played a significant role in Toronto hosting five CCAA Championships in one year; a most ambitious and successful major event which brought over 700 student-athletes to the GTA. Her leadership was also major factor in Seneca hosting a CCAA national soccer championship, and twice winning the CCAA men's soccer title. For her dedicated service, Zettel was awarded Seneca's Supreme Service Award and John Cruikshank Service Award.

After moving over to Centennial College, Zettel continued to work hard to serve her new school and athletes. She continued serving on the OCAA Executive from 1987-89 as treasurer; 1989-91 as vice president; 1991-93 as president; and 1993-95 as past president.

Mary continued to play a role in several OCAA committees until her retirement in 2007.