It is said that tedium is a disease of the idle or that it attacks only those who have nothing to do. But this ailment of the soul is in fact more subtle: it attacks people who are predisposed to it and those who work or who pretend they work (which in this case comes down to the same thing) are less apt to be spared than the truly idle.
Nothing is worse than the contrast between the natural splendour of the inner life, with its natural Indias and its unexplored lands and the squalor (even when it's not really squalid) of life's daily routine. And tedium is more oppressive when there's not the excuse of idleness. The tedium of those who strive hard is the worst of all.
Tedium is not the disease of being bored because there's nothing to do, but the more serious disease of feeling that there's nothing worth doing. This means that the more there is to do, the more tedium one will feel.
The Book of Disquiet, Fernando Pessoa