What are some good things to bring to a Music Festival?

I am going to the Mile High Music Festival in Denver, CO this weekend (July 19th & 20th) and am making a “things to bring in my backpack” list. It’s going to be pretty much too whole days of amazing music…and I’ll be on my feet probably the whole time… in 95 degree weather. What are some good things to bring, especially things that people wouldn’t think of unless they’ve actually gone to a long music festival.