Maybe he's exhausted. No President since FDR has had to deal with as much sh-t as he has. When Bill Clinton took over from Bush 41 in 1993 he had it so f[Inks]ing easy compared to the flaming bag of sh-t that Bush 43 left behind (who, by the way, took way too much vacation time).
No just stop, you really don't need to know very much about history, to know how big a pile of cattle fecal matter that comment were.
Every president from Eisenhower to Bush I had to deal with the threat of nuclear annihilation, that alone are much bigger problem than anything Obama have to deal with.You cannot compare personal attacks and "busy times at work". For great politicians, wars and crisis are not a source of stress and worries, but a source of excitement. It's their job and they like big challenges. Obama has to deal with nasty attacks on who he is and not on his actions, and it's always very mentally tiring.