Its my belief that since your past will always be history that should just be archived as a learning ground for things to come. There has been no particular person, philosopher or guide who imparted this piece of advice to me. All through my life, I have learnt a lot from people I have met, interacted or worked with,from religious scriptures and some interesting books on philosophy.
I would think that this is the most practical tool, specially in todays fast-moving world. It not only helps you enjoy your present moment but at the same time helps you define your future. This advice has guided me to deliver all the tasks both in my professional and personal life effectively. I live my life to the fullest every day and make the most of each moment.I treat every moment as gods grace showered upon me.