You are going to LOVE this bathroom mirror hack that I discovered on DIYHomeWorld.com: How to get no-fog mirrors in your bathroom, or wherever!
1. Gently rub a dry bar of soap over the mirror. Don't go crazy, just a small amount will do.
2. Using a dry clean cloth, buff the glass clean.
3. Using 1:1 ratio of water to glass cleaner, clean any soap residue that does not come off during the buffing process.
By following these steps you shouldn't need to do this again. Enjoy! <3