About 20% of your daily activities produce measurable and tangible results. An even lesser percentage produces measurable and tangible results that make you happy. Learning how to spend your time and energy on this 20% makes you more productive and happier with more leisure time. Allowing the other 80% to continue to occupy your mind is tiring, frustrating and unproductive. Vilfredo Federico Damaso Pareto first observed it in the beginning of the 20th century.