How can i motivate myself when it comes to doing an activity?

when i want to do anything, the thing i like most is motivation... whether it comes to studies, sports, or just any activity... i lack the motivation.. im good in most things but i can be so much better, the only reason im not is because i dont have any motivation .... how can i change that and be motivated?
self motivation stems from the need of accomplishment. It is a tool we use in order to get certain painful tasks done, even sometimes activities that we want to do. But sometimes the award of accomplishment is not enough for us to enjoy. Next time maybe think of finding ways to reward yourself once you have to do something you would rather not. ex. finish cleaning your room, reward yourself with maybe an ice-cream or something you enjoy doing.