Full Idea
It is one of the essentials of boredom that one's faculties must not be fully occupied.
Gist of Idea
Boredom always involves not being fully occupied
Source
Bertrand Russell (The Conquest of Happiness [1930], 4)
Book Reference
Russell,Bertrand: 'The Conquest of Happiness' [Unwin 1961], p.37
A Reaction
He gives running for your life as an example of non-boredom. I suspect that this is only the sort of boredom that troubled Russell, and not the sort of profound boredom that led the actor George Sanders to suicide (according to his last note).