Matt Damon was 17 in Mystic Pizza when he played the character 'Steamer'.
That was over 36 years ago in 1988.
This was his first recorded movie acting credit (although may not technically be his first actual acting role).
Today he is 53, and has starred in 110 movies in total, 106 of those since Mystic Pizza was released.
In Mystic Pizza, I think Matt Damon looks: