The Tuskegee Airmen Why they preform there duties so well during WWII when they were not welcome in America ?

The Tuskegee Airmen were the first African American military aviators in the United States armed forces. During World War II, African Americans in many U.S. states still were subject to racist Jim Crow laws.[N 1] The American military was racially segregated, as was much of the federal government. The Tuskegee Airmen were subject to racial discrimination, both within and outside the army. Despite these adversities, they trained and flew with distinction. Although the 477th Bombardment Group "worked up" on North American B-25 Mitchell bombers, they never served in combat; the Tuskegee 332nd Fighter Group was the only operational unit, first sent overseas as part of Operation Torch, then in action in Sicily and Italy, before being deployed as bomber escorts in Europe where they were particularly successful in their missions. So I ask what was there motivation to preform there duties when there was racism in America ?