What to carry when running a half?

Two months out from the actual race, I decided to run a half today. Just me and my phone, no water, nothing else. I finished in 2:39, and now I know that I really need to carry something, water bottle, some kind of food, something. Longest run I've had before today was a 10k!

So, when I go do this for real, what do I really need to have to not get fatigued and finish strong?