I suppose the author does'nt mean by fearlessness that we should dive alongside a great white shark, a feat I would'nt dare to commit, but which spectacularly demonstrates that when one has no fear one does'nt get harmed. Just the same, the fears which are lurking in the waters of our daily consciousness can cripple us as badly as the teeths of a Great White if we let them unattended.
Fears, or rather fear of living and ultimately of dying. How to separate one from the other when we are invited to die to the past every moment if we are to experience anything new, if we are to experience freedom to be and to do. How to deal with fear? We may turn to the teachers for guidance but we have to do the work ourselves.
The author, it seems, is saying that we must first come to contact with fear, face the feeling itself. Most likely we tend to avoid feeling the feeling itself. Mischievous thought is very good at the game of avoiding to feel. But if we are mindful to stick with the feeling and do not move away from it mentally we may discover that the feeling itself feels like sheer aliveness. Thich Naht Hanh goes further to say that the feeling is to be dearly embraced like one's own child.
When fear arises, we can watch thought's immediate reaction which is to suppress it or overcome it. Through observing more closely we may come to the realization that thought is both the source of fear and that which gives it a continuity. This is what J. Krishnamurti calls true meditation.