WHY SORROW COMES IN LIFE?

A Pupil went to his Master and asked a question. I do good for others and always thinks to improve people’s life but I could not understand why problems come my way. I always find myself in sadness (sorrow) and I think my sadness never has any end. Master smiled and put a question before the pupil if you borrow one lakh rupees from the bank and return 60 thousand rupees and forget about 40 thousand? But after years you deposit 40 thousand rupees into the bank but the bank deducts that amount, It is fair or not? pupil says  It’s fair because Bank deducted 40000 rupees because I had already borrowed from the bank; the Same formula applies in your Karma. Pupil said I could not understand what you said? Master replied when you do denied actions like telling a lie, cheating, threatening, or beating someone, your account of karma is filled with the wrong karma. When you do a good karma you start returning your bad karma. When you will do good, your account of bad karma will be closed and if you continue to do good karma your account of good karma will be filled with unlimited good karma and you will get unlimited happiness and prosperity in your life. So always do good for others because as you do today you will get in the future.