What do you mean, “Set personal core values”? There’s nothing to set. You’ve already got core values. You were born with them. They are there instinctively. Look no further than that little voice deep inside of you.
Think of it like buried treasure in an archeological dig. The treasure already exists, and was always there. It is just covered in sand and debris. It is your life’s work to expose the treasure, by removing the dirt one spoonful at a time.
Once you finally do, nothing you find there will really be all that surprising. After all, you’ve known all that you find there all along. It was just obscured by dirt and debris. The only thing that may turn out to be surprising is the fact that you doubted yourself in the first place, rather than trusting your instinct and just listening to your gut.