The dictionary defines happiness as a mental or emotional state of well-being defined by pleasant emotions ranging from contentment to euphoria. While philosophers, scientists and religious leaders have all tried to address this weighty issue time and again happiness still remains the biggest mystery. To many of us, it is a vague concept: everyone wants to be happy but we don't know where to start. If you are also sailing in the same boat then read on. These 10 facts will leave you happy. Promise.