Why does Chapter 8 claim that much of human life is wasted, and what are the stages it describes?

According to the philosophy presented in Chapter 8, a significant portion of human life is consumed by non-spiritual pursuits. It states that half of our life is spent just in sleep, while the rest is often spent in restlessness. The chapter breaks down the remaining time into distinct phases: childhood is spent in play, youth is dominated by passion and worldly desires, and old age is ultimately burdened by infirmity and constant disease. As Chapter 8 points out, these stages—childhood, youth, and old age—come and go naturally without us even noticing the exact transition, leading to a life potentially wasted if the true purpose of self-realization is not pursued.