Let's take a good look and see the truth whether we can control these feelings of happiness and suffering at all. Is it possible to just feel happy all the time without any pain? All the feelings in our heart, be it happiness, suffering, or neutral... they are subject to changes. They're beyond our control and they're not subject to our demand. These ever-changing feelings that are merely responding to causes and conditions - do they really exist such that we call them as "self"?