Not only has John Cena been on the WWE payroll for 13 years now, he has also proved to be the most willing WWE superstar of the last decade. If Vince says "jump, Cena responds "how high?". There is nothing the 14 time WWE Champion wouldn't do for the WWE. He has legitimately put the needs of the company above himself and his family - evidenced by his 2012 divorce. For Cena it is what he lives for, you get the feeling he really enjoys and takes pride in being the man who carries the WWE brand. He doesn't want to let that position slip and as such continues to represent the company with a level of intensity few want to take on. The Big Show recently noted in 'WWE 50' that Cena goes three months without going home. Do you think a CM Punk really wanted to be the number one guy? Do you think Punk really wanted Cena's schedule? Of course he didn't, circumstances which 'burned Punk out' are the same sort of circumstances which Cena relishes. He wants to be appearing in multiple media spots and promotional activities. He wants to be appearing on every WWE show. Vince can't get that level of loyalty out of any other superstar. John Cena's life and home is on the road, he is the real 'Mr No Days Off' and that's why he continues to be pushed as WWE's number 1 guy.