Bush seemingly became complacent and somewhat detached from his duties in the last two years of his Presidency after the Democrats took control of both Houses of Congress. It seemed, at times, that he just wanted to get it over with and go home to Texas.
With Obama, even before the mid term elections, when Republicans are predicted to take control of both Houses of Congress, we are seeing a completely detached President, who appears to have the desire to just get it over with. In fact, an Obama resignation would not be surprising, given his narcissistic tendencies and need for approval, if, indeed, the Republicans do gain control of the Senate. Obama talks a good and provocative game but has shown little willingness to actually become involved in a fight.
Maybe, a two term Presidency requires more stamina than either Bush or Obama have exhibited.