Sinfield has impressed in the two games since being handed the captaincy and the player has said that he will "have to pinch" himself to take in the past month of his career.
"The last month of the season with Leeds and [England coach Steve McNamara] naming me as captain and going to South Africa to spend some time with the players has been one of the most special moments of my career," he told the club's official site.
"I love being involved with the England squad. I love the way that Steve is driving it and it's a huge honour to be a part of it.
"I'd like to think in a few weeks' time when I have some down time that I'll be able to look back at 2012 with some fond memories and I'll probably have to pinch myself over how special it's been."
Sinfield has been at Leeds his entire club career.