50/50 and why

If life is 50/50, how do we know what emotions to allow and what emotions are needless suffering? If we could just redirect our thinking because a thought feels bad and we know it’s optional and all circumstances are neutral, wouldn’t be generally rarely feel negative emotion? I know the example of grief, and how sometimes we want to feel bad, but what about all the other examples in our lives that make up that 50%?

Or is the 50% negative emotion also including all of the emotions that come up that we must fully feel, process, and then let go of to reach our dreams?