According to Dr.Oz, "when making your own juice, try to make only as much as you can consume at one time. Juice that isn’t consumed right away can harbor bacteria and cause food poisoning. Exposure of the drink to air, bacteria and other pathogens can not only make you sick but threaten the nutritional value of the juice as well. More on Juice Safety
Educated yourself before you start...
It's important to be well informed on juicing before plunging into this trending new diet. Please watch this video on Juicing
Also did you know there are certain vegetables you should not juice unless organic. According Mercola.com, you should buy organic celery, spinach, kale, collard greens, lettuce, carrots and cucumbers.
Natural News states if you're looking for a simple, natural way to increase the length of your workouts, or if you just want to give yourself that little edge in endurance or speed, then beet juice may be the answer.