I think most people intuitively agree that increasing their own well-being and minimizing their own suffering are the right things to do. Everyone wants to be happy, enjoy a good health, etc. The whole Maslow's hierarchy of needs is a thing for a reason. Some would go one step further and claim that not only our own well-being matters, but others' well-being matters too (thus supporting moral obligations toward other conscious beings, altruistic behavior, etc.). But in any case, the pursuit of well-being and the avoidance of suffering always appear to be at the core of any moral/ethical system if scrutinized deeply enough. Even a religious person who wants to go to Heaven and escape eternity in Hell could be said to be rationally justified in their preference based on the fact that Heaven will maximize their well-being and minimize their suffering, whereas Hell would be the polar opposite of that.
However, all of this relies on a fundamental axiom or premise, and that is that pursuing well-being and avoiding suffering are fundamentally good things to begin with. Are there any good reasons to assume that? Why not maximize suffering and minimize well-being instead (in which case "going to Hell" would be the optimum)? Are there objective reasons to consider the pursuit of well-being and the avoidance of suffering to be the right things to do?