He grew up shortly after the depression with a family of limited means where he learned the importance of a work ethic and the necessity of thrift.

At East Los Angeles, he specialized in distance swimming, making the Junior College All-American team in the 1500-meter event.

[3] After marrying his wife Teddy on March 14, 1953, he went to work full time and then enlisted in the Navy reserves before graduating college.

Returning to complete his studies at California State, Los Angeles, he also played center and linebacker on their Football team for a year.

[4] From around 1956-57, he served in the Navy and swam for the All-Navy "B" team, competing occasionally in intercollegiate swimming competition and water polo.

[3] While serving on the U.S. Navy Destroyer USS Cunningham, he was able to attend though not compete in the swimming portion of the 1956 Melbourne Olympics.

Football at El Monte High School and worked as a lifeguard at the end of 1957 upon his return from Naval service.

[3] Returning to college studies around 1957 after his service in the Navy, he completed his BA and Master's degree while attending California State at Los Angeles around 1960.

[2][5] In 1958, after his Navy service, Don had his first position as a fulltime teacher, instructing Social Studies at California's Rosemead High School, where he also coached J.V.

In the Spring of 1958, he also took over coaching the Rosemead High School's swim team, a role that would soon direct his career focus.

Top women swimmers coached by Gambril at Rosemead by 1961 included Jeanne Hallock Craig, Sharon Stouder, and Pam Crotwell.

Looking back on their experience, the women at City of Commerce believed Gambril was a brilliant marketer who convinced them they could be the best in the world, and remembered him as a "tough but tender-hearted leader."

1972 Olympian Silver medalist Hans Fassnacht, from Germany, would set the world record for the 400-meter free in 1968 under Don's guidance at Long Beach.

[2] Gambril coached many well-known Olympic swimmers, including Mark Spitz, Sharon Stouder, and Gunnar Larsson (Sweden), Matt Biondi, Nancy Hogshead, Jonty Skinner (South Africa), Hans Fassnacht (Germany)[11] and Mary T. Meagher.

He coached 1964 Canadian Olympian Barbara Hounsell, who swam for a period with the Whittier Swim Association in the Los Angeles area and 1972 Olympic 100-meter Bronze medalist Robin Backhaus.

During his tenure, he also coached future Hall of Fame swimmer and Alabama Swim team three-time MVP Jonty Skinner (1975-1977), who would break the 100-meter freestyle world record in 1976 three weeks after the summer Olympics.

He changed his diet, lost weight, and made a thorough recovery, continuing to coach Alabama swimming for another nine years.