Hey Ujjwal, 

*Set your goal clear. Make short goals for everyday and prepare a to-do-list to track your day to day productivity. When you are productive you become more confident.

*Try to perform well in mock tests. This will boost your confidence and you'll have eagerness to study. Even if you don't score well do not get demotivated. Talk to your teachers where you need to improve.

*Make a group of friends you share the same goal as you and motivate you. In this way a healthy competitive atmosphere is created.

Remember your goal and take baby steps everyday to get closer and closer to your target and you'll do wonders!

All the best and good luck !