A stronger approach is to create a mantra that you say in front of the mirror every morning. It's more powerful than writing on the mirror as you're speaking it into existence. You can actually do both for the ultimate effect. Use the positive reflections you wrote on the mirror as your mantra and if you don't have time to recite your mantra every morning, you still have the writing on the mirror. Let's face it, no matter how much in a hurry you are, do you ever forget to glance at the mirror?
I've used the "writing on the mirror" method for what I want to achieve out of life and it keeps me peaceful, motivated and joyful. Using one or both of these methods will likely do the same for you as it relates to your confidence level and loving yourself just the way you are.