One of the best and well-known quotes is the boy scout "be prepared." I think this is one of the best advice you can give especially when it comes to being healthy. Part of being responsible for the health of you body is thinking ahead.
If you know you are going to a party where there may be snacks than simply eat healthy before, don't arrive hungry. If you are working late or find yourself working through lunch often, pack a healthy brown bag lunch. It may not be the most exciting meal but it will keep you from inhaling an unhealthy take out. If you have a no time to prepare breakfast in the morning, do it the night before. These suggestions may seem logical but I am amused at how many people do not make the effort. Taking five to ten minutes to think and prepare ahead, will keep you healthy and slim for years. Isn't your health worth ten minutes?