A farmer generally uses a silo, which is a tower or pit on a farm, to store grains.You put some grains from the top of the silo; it comes down and you collect the grains at the bottom.Now, suppose the farmer puts very cheap, and rotten grains in his silo. And then he realizes from eating all those bad grains that it is not good for him , it is not good for his family. “Henceforth, I am going to use good grains.” Then he starts putting good grains, and better grains, and very very nice grains in the silo from top; but still he receives bad grains at the bottom.That means he is suffering for the past. But in future there is going to be great prosperity because of what he is doing now.
Similarly there are people who have been very pious and good in the past and they are getting the good grains of much prosperity and happiness. But because they are engaging in sinful activities now, they are putting the rotten grains on the top, and it is just a matter of time, till it all comes upon them.