Self-doubt is not the territory of young men in their twenties

The Sunday Philosophy Club by Alexander McCall Smith. Page 99.

If she had known him hardly at all before she called on the flat in Warrender Park Terrace, she did not know him any better now. He had been a pleasant young man, popular and not given to self-doubt; no surprise, perhaps, as self-doubt is the territory of the teenager and, much later, of the failing, not of young men in their twenties. If he had been concerned about something, then his concern must have been hidden from those who were closest to him in his daily life.