The New York Giants selected the former Syracuse player in the fourth round of the draft over the weekend to be backup to their current starter.
Manning told Newsday: "I understand that one day it will end. You never know what's going to happen, so you have to take advantage of it and work hard to make sure that every year that you play, you do everything you can to win another championship.
"I think it's always good to have a young quarterback who can come in and be prepared. You never know what happens in this league and you always have to have quality players on your team at quarterback."
The 32-year-old, who is entering his 10th season with the Giants, has not missed a game since 2004.