I saw a crockpot recipe on twopeas that I thought sounded good, and, as it turns out, I was right.
one pack of chicken breasts (I used three big ones from the Costco bag)
1-2 packages of taco seasoning
one can of diced tomatoes with green chilies (a can of Mild Rotel worked great)
Sprinkle some taco seasoning on the bottom. Add the chicken breasts. Sprinkle more seasoning on top. Cover with the tomatoes. I drained mine just a little. Cook on low til the meat is cooked and shred. (At this point I added a little more taco seasoning because it needed it. I also scooped back in the tomatoes, but not the juice.) Serve with your favorite taco toppings.
Bonus: The leftovers tasted better the next day!