Because complete focus nai hota.. This is due to lack of focus, dedication and determination to go ahead and life just filled kg distractions and fun things. So I better suggest you do some activities like a walk, or yoga to increase your concentration and then tell yourself the need and importance of studies for your future, also try to avoid distractions like social media, internet and every such things.

Then you may reach towards the success path.

Thank you. best wishes.