By 1966 , when he was 22 years old , Castillo began to hit his stride .
After serving the kind of grueling apprenticeship that no longer exists in boxing , Castillo began to edge into the top ranks .
By 1966 , when Castillo was 22 years old , Castillo began to hit Castillo 's stride .
After serving the kind of grueling apprenticeship that no longer exists in boxing , Castillo began to edge into the top ranks .