To explain the source of morality by asserting a prior moral rule, in this case, that one should be "life-affirming", begs the question of where morality came from in the first place. Why is it incumbent upon me to be life-affirming in the future? In the absence of an absolute, transcendent ethic there is no evil or good in the first place, only personal preference; the things that are called call "good" and "evil" are just impersonal, valueless data with no explanation and no meaning.
Cordially,
I've been trying to think of a single instance of a successful religion or moral system that sold itself to its followers by holding out the hope of an eventual reward of poverty, pain, loneliness, degradation, regret, and death.
Can you think of any? Doesn't the question itself seem absurd? I say it's axiomatic that the purpose of morality is to enhance our lives. Any discussion of morality kind of falls apart at the start without that a priori assumption. Any motivation to even worry about such questions in the first place falls apart at the start without it.