In my Tip # 2 I explained that you do a lot of walking on tour which means that you are exerting a lot of energy. It is important that while you are on tour you are making the right choices to keep your energy up. Bring small healthy snacks to keep in your day bag such as trail mix or granola bars.
I also can’t stress enough the importance of staying hydrated, especially when traveling during the warm weather months. I always make sure I have a refillable water bottle in my backpack. Some of the attractions (especially Washington DC) don’t allow liquids of any sort but I can dump out the water beforehand and then just refill at the next available water fountain which are generally easy to come across.