Group Captain Singh is now battling for life at a military hospital in Bengaluru.
He was conferred with the Shaurya Chakra in August for averting a possible mid-air accident after his Tejas light combat aircraft suffered a major technical glitch last year.
"It is ok to be mediocre. Not everyone will excel at school and not everyone will be able to score in the 90s. If you do, it's an amazing achievement and must be applauded," Group Captain Singh wrote in the letter to the principal of the Army Public School in Chandimandir in Haryana.
"However, if you don't, do not think that you are meant to be mediocre. You may be mediocre in school but it is by no means a measure of things to come in life," he said.
"Find your calling, it could be art, music, graphic design. literature etc. Whatever you work towards, be dedicated, do your best. Never go to bed thinking I could have put in more effort," he added.
The air warrior said he was an average student and barely scored first division in 12th standard, but had a passion for airplanes and aviation. I
"I write to you filled with a sense of pride and humility. On August 15 this year, I have been awarded Shaurya Chakra by the President of India in recognition of an act of gallantry on October 12, 2020," he said.
"I credit this prestigious award to all those I have been associated with over the years in school, NDA and thereafter the Air Force, as I firmly believe that my actions that day were a result of the grooming and mentoring by my teachers. instructors and peers over the years," Group Captain Singh wrote in the letter dated September 18.
The Group Captain said he was not trying to blow his own trumpet or writing with a desire to seek a pat on the back, and that he wanted to let the children know a few of his life's experiences that may help them in future.
"I was a very average student who barely scored first division in 12 class. Even though I was made the Discipline Prefect in 12th I was equally average even in sports and other co-curricular activities. But I had a passion for airplanes and aviation," he wrote.
Group Captain Singh was conferred with the Shaurya Chakra for displaying exemplary composure and skill when his Tejas aircraft developed the technical snag during a sortie last year.
"Despite being in extreme physical and mental stress in an extreme life-threatening situation, he maintained exemplary composure and recovered the aircraft, thereby exhibiting exceptional flying skill," the award citation said.
Group Captain Singh was on board the Russian-made chopper as the liaison officer for the visit of CDS Gen Bipin Rawat to the Defence Services Staff College in Wellington.