Do your duty and that's it
Karmanyevadhikarasthe Maphaleshu Kadachana|
Ma karma Phalahe Turbhuhu Matesangosthwakarmani||
The most famous verse that summarises the Bhagavad Gita, tells us that we have the authority only over our action. we have all the right to give our 100 per cent of being to any action and no control over the results of our action whatsoever. The student can study excellently well for an exam and that is up to him. He may get lesser marks than expected and the reasons may be beyond him.
At the same time, Krishna says, never consider yourself as the cause for the results of your activities (if you have given your 100 per cent effort, that is!) and never get attached to the idea of escaping from the work you are supposed to do in your life. - Swahilya Shambhavi.
(A pony going about its work of taking a pilgrim around the parikrama at Mt. Kailash.)