When you are very small every move you make is an occasion for celebration for your parents. Grasping an object, turning on your back, sitting, crawling, standing, taking the first few steps, uttering your first words - you pass these milestones with your own efforts and as you score each of these goals you are cheered and hugged by your parents and you feel good. As you grow and gain mastery over your movements and speech and set to conquer a New World something happens. You are no longer cheered. Often you are told what not to do. More obstacles are placed. And slowly you find yourself doing things you are asked to do rather than what you want to do.
When goals are set by yourself as when you decide to learn cycling or swimming you experience a joy when you achieve success. But when goals are set by others as when you are asked to learn by heart a multiplication table, you find that the joy of scoring your goal has been taken away from you.
You cannot do much about various tasks set for you. Try to understand the purpose of each activity you are engaged in. This will help you to find the task meaningful. Pursue the task with a positive mind and when you complete the task you will feel a sense of satisfaction. This feeling of self-satisfaction is something close to the joy you felt when you could ride the bicycle yourself.
Besides the tasks you are required to do, however meaningful and useful they are, set a task for yourself that no one has asked you to do. The task could be any thing - going for a jog, solving the crossword puzzle in the newspaper or learning football. Just do it because you want to do it. It'll help you develop confidence in your own abilities.