Get a good night's sleep, eat healthy food and exercise daily.

drinks vitamin c :)

You stay strong and maintain energy by eating nutritious food, getting enough sleep at night, and being careful not to be around germs, viruses, sick people, and washing your hands frequently. Germs, bacteria and viruses can be carried from the environment on your hands to your mouth, so sanitizing your hands is a big help. I take a multi-vitamin every day to be sure I get all the vitamins I need, but if you eat the proper food you will get your vitamin A, B, C, D, E and proteins you need. There is one other area that needs attention. You need to exercise, walk a lot and be physically active to have a strong heart and strong muscles. If you do this, you will surely maintain your energy level.

Starting a question with "'how to" is Chinglish. There are a number of ways to ask the question in English: "How does one keep up one's energy?" However,that one might sound a bit formal. "How do I maintain my energy level?" That's a little more 白话. "What should I do to have more energy?" As to the answer, I've found from personal experience that the best way to stay in shape, that is to maintain an adequate energy level, is regular exercise.

I wouldn't recommend drinking energy drinks nor too much coffee, since they are more useful to athletes than to people who just want to have their energy back. In the long run they will just deprive you of your sleep. I agree with fdmaxey, Number one is much better. Have a regular life, sleep, make sport... and dance! :D Even better if you find someone to dance with ;D