Previewing changes?

What would be the easiest way to have someone else preview changes to a page? I have a page that is currently published and I need to update it but I need to send the unpublished changes to someone to approve prior to making them live. I tried using the link that comes up when you click the ‘Preview Changes’ button but apparently unless the person is logged in with my account you get a message that says you don’t have permission to view preview drafts. Is there a simple way to accomplish this?