I am 16 years old and I want to know about some healthy energy drinks that I can drink while my regular exercise. I do 30 minutes of exercise daily and sometimes after my exercise I feel very tired and restless. My friend told me about healthy energy drinks which are low in calories and sugar. I want to know which is the best energy drink that is available in market and how many times I need to drink it to make me feel good and healthy. Is it enough to drink once in a day?