Amusingly, he kept meticulous count of the times when he was fitted with 'hobbit feet' and subsequently the feet were never 'in shot'.
He suffered an injury during the filming of the scene at Parth Galen when Samwise Gamgee runs into the river after Frodo Baggins - there was a shard of glass in the river bed and Sean Astin's foot was pierced and bled profusely. Despite the injury he was back on set the next day.
Both of his parents worked in the film industry: his father John Astin created the character of Gomez Addams in the TV series "The Addams Family" while his mother, Patty Duke, won an Oscar for her performance in "The Miracle Worker".
Sean Astin wrote a painfully honest account of his work on The Lord of the Rings films in his book "There and Back Again".