Life is difficult, and accepting that is the beginning of maturity
Peck opens with the flat statement that life is difficult, arguing that most people's unhappiness stems less from the difficulties themselves than from an unconscious, persistent expectation that life should be easy, or should have been easier for them specifically than it has been. That mismatched expectation generates ongoing resentment, self-pity, and a sense of being uniquely burdened.
Once a person genuinely accepts that difficulty is the normal condition of life rather than a personal exception or injustice, Peck argues something shifts: problems become expected work to be done rather than unfair impositions to be resented. This acceptance doesn't remove suffering, but it removes an entire secondary layer of suffering caused by fighting the fact that suffering exists at all.
He treats this acceptance as a genuine turning point in psychological development — not a one-time realization but an ongoing discipline that has to be renewed whenever new difficulties arrive and tempt a person back toward feeling singled out by misfortune.
Takeaway: much of the pain in hardship comes from resisting the idea that hardship is normal, not from the hardship itself.