I have completed year 1. The science department does not offer summer classes and the only summer class i enroll is africa studies. I am self studying this summer. But i have a problem of concentration. I often go to watch nba playoffs and youtubes after i have read through a few pages(though i am interested in that subject). When there is a choice between easy thing(say nba playoffs) and difficult thing(say differential equations), i 99.9% will choose to do the former. Why can some people be so motivated that they can stay at home and spend most of the day solving problems and read difficult books? So i waste a lot of time in entertainment. Worse still, my study method is that i only read the books but i don't have the motivation of practising the problems as they are much more difficult than reading. Therefore i find my productivity in self-study only about 5% of the time when i took my classes and have assignments to do. I try to make some study plans but they do not work because i found watching nba playoffs more satisfying than fulfilling the study plan(of course i now regret it). I have no competitions or internship to join this summer. How can i complete a math/physics course(say differential equations)in this summer by self-study without the stimulation/motivation from the outside world? It seems that i only work hard when there is someone to compete with.