Sen. John McCain (R-Ariz.) in a new profile worries aloud about the physical effects of retirement, but also says he doesn't want to grow too old in the Senate.

McCain has said previously that he is considering seeking reelection in 2014, when he will be 80. He said in a lengthy piece written by The New York Times's Mark Leibovich that he's aware that people who no longer have something driving them often atrophy.