John Cena continues to delay time off from the road as WWE is trying to book him in situations that won't be physically taxing. This is the reason for his program with John Laurinaitis.
With Cena's divorce and other issues, he doesn't want to come off the road to give his body some rest to heal up because work is how is choosing to deal with the problems in his personal life. WWE has a long history of top guys getting burned out or breaking down mentally and the company is doing everything they can to keep Cena in a good frame of mind and make sure he's given a bit of a break physically, even while he refuses to actually take a break.
I'm told even by toning things down, as bad as Cena's hip is, he could still be making things worse. However, Cena is obviously well-liked by the office with considerable influence, so when he said he wanted to stick around as long as possible while he dealt with his divorce, no one wanted to tell him no.