There once a shepherd. One day he was checking his flock when he noticed a sheep was missing. Seeing that the gate was secured, he began to inspect the fence surrounding the pasture with the help of his neighbor. In one of the corners sure enough the found a hole and a fresh pair of wolf prints.
His neighbor worriedly warned him to fix the hole or else the wolves would come again. The shepherd upon hearing this advice thought, "The sheep has already been lost, what use is fixing the fence?" With that he pushed the thought of wolves and fences to the back of his mind. The next day, whilst counting his sheep he found another missing, with fresh paws prints around the same hole in the fences.
He was regretful for his foolishness and with the help of his neighbor fixed the fence, and hadn't lost another sheep.
Often when one meets misfortune he can only learn from the experience and move on. What is important is that we should learn from our mistakes and immediately rectify the problems to avoid future loss.