Gita says that a realized soul who uses the analysis by intelligence leaves the concepts of both happiness obtained by doing good deeds and misery obtained by doing bad deeds (Buddhi Yukto Jahatiha Ubhe Sukruta Dushkrute).
This means that you are trying for the temporary happiness of heaven and trying to avoid the temporary misery of hell here as well as in the upper world.
This means that if you are analyzing the scriptures with sharp logic to realize the ultimate goal of the human life, you will not be interested in neither happiness nor in misery during the life as well as after death.
The ultimate goal of life is not anything related to your self, because it is aimed at pleasing the creator since the original aim of this creation is only the pleasure of the Lord through entertainment.
Therefore, the original aim of yourself, other selves and the entire universe is only to serve the Lord and please Him.
Then, you will be blessed by the Lord with His eternal divine grace and your life is fulfilled.
Therefore, the human life is neither for doing good deeds nor for doing bad deeds and it is also not for enjoying the good fruits or bad fruits. You are wasting the human life in doing good works and some times doing bad works due to the force of your ignorance.
By this very little time is left over here to serve the Lord.
If this little time is also used for enjoying good and bad fruits, no time is left for you to do the service to God and get His blessings. Hence, to save at least this little time for realization of spiritual knowledge and subsequent involvement in the divine service, at least the enjoyment of good and bad deeds is postponed to a latter time and at a latter place.
The latter time is after death and latter places are hell and heaven.
This is the reason for creation of hell and heaven separately to enjoy the results after death.