“करम करो फल की चिंता मत करो”~भगवद् गीता
This shloka is applicable in every aspect of our life.
Staying calm and composed emotionally and doing what we are meant to do everyday as a practice, the results will become immaterial one day.
Like in golf- if even for a millisecond you deviate, you miss the target, similarly while studying if you allow distractions even for a fraction of time, you distract yourself from achieving the desired goal.
The aim is to work hard and focus, and not worry about the outcome.