I have just decided on a whim that I no longer want to support the dairy industry and cut it out of my diet cold turkey. I've already trialed a run and I felt great but it was so difficult. Never realized how much dairy was in my diet in basically everything I ate and it wasn't long before I ran out of things to eat that didn't contain it. Even subjected myself to eating cereal with water which was extremely unpleasant. It's been hard but I know you're the community to ask for help because you've probably went through this sort of thing before.
Check out milk alternatives like oat milk, rice milk, almond milk, hemp milk, coconut milk, soy milk, etc. I've personally found oat is quite good, and it also comes in low on the water usage scale.