This is the current raising problem for all the students so first you have to think that what is my main moto and what is my outcome to study for it and why should i study this and that gives you a clarity about what to achieve and what to study and clarity about your future . Every time while studying you have to have a question in your mind that "IS WHAT AM I DOING IS USEFUL FOR ME OR NOT" do only the things which are useful for you and dont do the things which are useless for you and gives a temporary happiness for you , your the own constructor of your life and if you dont construct it well and plan it well you will be the destructer of your own life so always have that question in your mind "am i constructer or destructor of my mind" , so hope that these can change you a lot and you get succeded in your life