It depends on who you are and the activity that you are doing. If you are an athlete, you should drink 4-8 ounces 30 minutes before your competition or training, and then sip during workout or event. If you are on the job (for example, a firefighter or a construction worker), drink 16-24 hours throughout the day. If it is hot, or your activity becomes more intense, then you may want to adjust the amount of VItalyte you take accordingly.