Combine all ingredients in the bowl of a slow cooker. Toss gently to combine. Cover and cook on low for 6-8 hours, or on high for 3-4 hours, or until the beef is tender and falls apart easily when shredded with a fork.
Using two forks, shred the beef into bite-sized pieces. Remove the bay leaves. Serve immediately or store in a container in the fridge for 5 days or freeze.