Backing up yourself and reducing any negative self talk DURING the actual exam. Know that one may suffer, may be hard pressed but can still clear if you implement your learnings from prep.
Failed to realise this and missed out with 95 score in 2019. In 2020, similar fate awaited me, with me not knowing first 8-9 history questions and confidence dipping. But this time, above wisdom prevailed upon me and scored 127.
Take away is not to look at 127 but, if you can withstand pressure and willing to suffer and carry on for a little while more, you will be rewarded for your efforts.
Prelims paper on D day is like a tsunami wave hitting, scrambling/disorienting minds and then it says, common lets play the game now. So need to devise a counter plan and play the game in head before (my perspective)
PS: Luck is another dimension that's always present.
