The Bhagwad Gita says, 'Do your allotted work but renounce its fruit - be detached and work - have no desire for the reward and work.'
We should perform our duties without worrying about the results. If we start thinking too much about the results, then we will not be able to perform the assigned tasks properly. Then the final results will be unfair. So, its better to give 100% to the allotted work rather then worrying about the results.
The Bhagwad Gita describes the battle between the Pandavas and Kauravas, or we can say it describes the fight between the positive and negative qualities of a person. We can assume human body as Kurukshetra(a place where battle was fought between Kauravas and pandavas) and pandavas as positive and kauravas as negative qualities.
We all have both positive and negative qualities and a continuous battle resides in us. It depends on our thinking and surrounding environment who wins, whether positive or negative qualities and the result of this battle decides the real environment of this world.