How can I sleep early at night?

The trick is to just get yourself in bed, shoot for at least 9pm and try reading a book. Don’t look at your phone. You may be more tired than you think and even if you don’t fall asleep right away the first night, make it a habit to get into bed at the same hour to train your body for that evening routine of getting to bed on time.

Do a lot during the day. Exercise daily! Its better to aim for 1 pushup a day than setting an unrealistic goal.
This way you will automatically be tired in the evening!