The Chasam Sofer says that a tzadik can improve himself differently. It says סור מרע ועשה טוב turn away from bad and do good, how? בקש שלום ורדפהו, look for peace and pursue it. How do we pursue it? The guf and neshama are constantly in conflict, so we would like to make peace between them. We will create a small conflict having the neshama do something small that the guf does not like and then allow the guf to get used to it. Once it gets used to it, we have peace. Now, continue the method. Having to work this technique diminishes olam hazeh but a tzadik must continue to improve oneself and thereby one gains olam habo. Yaakov Avinu wanted to stop following this method so he had to worry about gaining olam habo through the tzaros of Yosef as above.