In conjunction with planning your meals, making healthy meals in advance and then freezing them is one way to have meals made for the times that you want to have something ready and healthy but that requires that it had been prepared at some point in time.
Another part to this is to buy healthy meats, fruits, etc. when they are on sale and to freeze them. Be sure that they are healthy and free of things we should not be eating (because these unhealthy meats or meats with unhealthy chemicals/content/etc. are often the meats that go on sale).
Frozen grapes are a great sweet snack!