You're going to get thirsty at band practice most likely, so bring water or Gatorade or something else you'd enjoy sipping on. The hardest thing about addictions is being able to simply stop behavior. Your body gets thirsty. Body signals brain. You grab beer. That is a hard signal to ignore, because it's a physical compulsion. So it's important to find "replacements" for our vices. Gatorade to replace beer, gym time to replace idle time or couch time, etc. The urges will come, no doubt, so if you have something you can do about it (replacement activity) you are in a far more powerful position than just trying to ignore those signals.