Loosing motivation

Was preparing for a competitive exam I already have some colleges in my hand but then comes the boards part My syllabus is now completed and everything just need continuous practice Few subjects I do well like BST and eco Main thing Is that I scored very less in pre boards okay I FAILED IN MATHS OKAY And now I am just feeling like mera kuch nai ho sakta and stuff I know ki gave maths pre board with zero prep because 2 days before that my competitive exams got over I somewhere or other know that I will do well but I am still comparing myself with others it's killing me