I love to do pactically questions then theory, i am v. good at solving practical ques't , i dislike learning.

I feel that i have the potiential to do good. But sometimes i just loss my confidence level i don't know wht to do. i have a bad habit of thinking too much something or the other always is there on my mind and so i fail. i wanna win the race. Plz help me, i am too scared about this.as this can make my career weak.