The senator, who ran for president this year, is now the presumptive Democratic vice presidential nominee.
Biden, now the attorney general of Delaware, was severely injured in 1972 in a car crash that killed his mother and younger sister. His father, who had just been elected to the Senate, took the oath of office in the hospital room where Beau and his younger brother were recuperating.
"My grandmom has a phrase, you know, there's a reason for everything," Biden told "Good Morning America." "And the other one that you know is that, you know, you're not given a cross you can't bear. And my dad wore it and did it with dignity and did it with a focus on his boys. And I've been a lucky, lucky son as a result."
Biden said that he and his brother, Robert, pushed his father to propose to his second wife, Jill. The brothers joined the couple for the first two days of the honeymoon.