The Buddha said that there are eight sufferings in life: the suffering of birth, the suffering of old age, the suffering of illness, the suffering of death, the suffering of love and separation, the suffering of resentment and hatred, the suffering of the five yin beings flaring, and the suffering of not getting what you want.
The most painful thing for all sentient beings in the six-path reincarnation world is not being able to get what they want. We cannot seek life, so birth is painful; we cannot seek youth, so old age is painful; we cannot seek health, so illness is painful; we cannot seek eternal life, so death is painful; we cannot seek reunion, so love and separation are painful; we cannot seek liberation, so resentment and hatred are painful; we cannot seek clarity, so the five yin blazing is painful.
If you want to achieve enlightenment and become an immortal, you will be unable to achieve it. If you have nothing to ask for and nothing to desire, what is there to love about life, and why do we need to live together in this world?
The beauty of the world also lies in thinking and seeking.