The quote suggests that the individual sees boredom as a significant and powerful adversary that threatens his well-being. It’s portrayed as an enemy that he must confront, and his success in overcoming it depends on whether he endures the process of dealing with boredom.
The author, Dorothy Dunnett, emphasizes that overcoming boredom is a challenging ordeal. The outcome depends on the person’s resilience, implying that enduring this experience might lead to growth, or else be detrimental if one cannot survive the confronting nature of boredom.