"A wish to escape from boredom is natural; indeed, all races of mankind have displayed it as opportunity occurred. When savages have first tasted liquor at the hands of the white men, they have found at last an escape from age-old tedium, and except when the Government has interfered they have drunk themselves into a riotous death. Wars, pogroms, and persecutions have all been part of the flight from boredom." [page 51]
"A life too full of excitement is an exhausting life, in which continually stronger stimuli are needed to give the thrill that has come to be thought of as an essential part of pleasure. ... There is an element of boredom which is inseparable from the avoidance of too much excitement, and too much excitement not only undermines the health, but dulls the palate for every kind of pleasure, substituting titillations for profound organic satisfactions, cleverness for wisdom, and jagged surprises for beauty. ... A certain power of enduring boredom is therefore essential to a happy life, and is one of the things that ought to be taught to the young." [page 52]
"A boy or young man who has some serious constructive purpose will endure a great deal of boredom if he finds that it is necessary by the way. But constructive purposes do not easily form themselves in a boy's mind if he is living a life full of distractions and dissipations, for in that case his thoughts will always be directed towards the next pleasure rather than towards the distant achievement. For all these reasons a generation that cannot endure boredom will be a generation of little men, of men unduly divorced from the slow processes of nature, of men in whom every vital impulse slowly withers, as though they were cut flowers in a vase." [page 54]
It's too long to reproduce here, but be sure to read from "I do not like mystical language and yet ... " on page 54 to the end of the chapter on page 56. This section is as close to paganism as you will ever see Russell come.
"Among those who are rich enough to choose their way of life, the particular kind of unendurable boredom from which they suffer is due, paradoxically as this may seem, to their fear of boredom. In flying from the fructifying kind of boredom, they fall prey to the other far worse kind." [page 56]