McCain refuses to say if he's healthy enough to handle 8 years as president

Just watched something rather creepy on ABC News.

ABC CORRESPONDENT: McCain is 71. Today he was asked if he has the health and endurance to serve two terms as president.

JOHN MCCAIN: You shouldn't run for 8 years. I'm running for a four year term.

Actually, the appropriate answer is "hell yeah, I can handle 20 years as president." I'm wondering if the increasingly fragile-looking McCain can handle even four.