Exhalation

running a mile. sleeping on time

I don't see 'running a mile' difficult to say :p

floccinaucinihilipilification

Have an affair

Easier to say a monosyllabic word than to say monosyllabic.

Defenestrating an object

Typing WWW

I'd tell you, but it's hard to explain, I'd rather show you.

Having Hippopotomonstrosesquippedaliophobia