Here's a few sakhis that may help explain Dukh and sukh

Two shopkeepers had their shops next to one another. The Gurmukh (follower of the Guru's (Gur) words (mukh)) used to go to sadh sangat every day and have darshan of Guru Nanak Dev ji do seva and come home. The manmukh (follower of his mind's (man) mukh (words) ) used to go to meet a prostitute. One day the GurMukh said come with me to the sadh sangat, after some persuasion the manmukh agreed, on the way the manmukh remembered his prostitute and backed out of going to the sadh sangat. He said I'm going to go to my normal activities but I'll meet you at the tree across the road tonight. The manmukh went to see the prostitute but she wasn't there so he arrived at the tree much earlier than expected. While waiting for the Gurmukh he started poking a twig into the ground. He found a gold coin, he quickly dug more and more but he only found a pile of ashes. When the Gurmukh returned he was limping along he'd stepped on a thorn. The manmukh said I do my dirty deeds and get good luck you do good deeds but get bad luck. The Gurmukh said lets ask Guru jee to explain. Guru ji told the manmukh, in your previous life you donated one gold piece to a Sant, for doing such a virtuous deed you were to recieve the rewards in this life of many gold coins. But because of your sinful deeds you burned your reward away and were left with your original gold coin. The Gurmukh was told, in your previous life you killed someone with a wooden spear, in this life you were to be killed in the same way, but because of your seva to the Guru you bad deed has been reduced to being pricked with a thorn.

MORAL: The Pains and pleasures one gets in this life are heavily influenced by past actions, not just in this life but in countless previous lives. When people suffer at the hands of others its because they made that person suffer in a previous life. Most people will take revenge and so the cycle of making each other suffer continues life after life. A mythical story to explain this is of a goat and a butcher. The butcher would kill the goat in one life ,the goat' soul would be reborn as a butcher and the butcher's soul would be reborn as a goat. In the next life the butcher would kill the goat and so the cycle continued. Then in one life the butcher received a customer who only wanted a goat's leg. The butcher thought if I kill the goat and sell the leg the rest of the goat will rot away. So what he thought was I'll just chop the goat' leg off and bandage the wound, that way the goat will stay alive until the next customer. Just as he was about to cut the leg, the goat spoke 'O Butcher, what's this new bad action you're starting? Life after life we keep swapping roles to cancel our actions, but if you chop my leg now and make me suffer in the next life I'll do the same to you and you'll suffer too!'