Tsukini kawatte oshioki yo!
Traits: transformation, friendship, hidden strength
The Magical Girl isn't just any old archetype. She's one of the most popular, most-invoked archetypes in Japanese comics and animation. She's been built up, deconstructed and reimagined. Hell, I'm not even the first one to use the Magical Girl as a magical archetype.
(Also, if you're a fan of Sailor Moon in particular, I recommend checking out Serenitism, it's an interesting take on a spiritual path based on the mythology of Sailor Moon.)
If you're feeling stuck in a mundane life, you may need to invoke the Magical Girl. She knows the value of the everyday because that's her downtime, but what she seems is definitely not all she is.
The easiest way to invoke her is to get home from work or school, change into a completely different outfit, and go do something exciting that would surprise the people around you. If going out with your witchy friends is an option, you can do that. If you don't have a lot of witchy friends, or the time and money to go out, that doesn't mean you're out of luck, though. You can go out by yourself or with another adventurous friend and try all kinds of things - a blacksmithing class, a burlesque show, skydiving lessons, or anything else you've always thought sounded like fun but worried was the kind of thing other people did.
Failing that, hold aloft your sword and yell "for the honor of Greyskull!" Or maybe that one only works in Etheria.
Magical Girl is also useful when you're in an environment where you feel you have to be closeted about some aspect of yourself - your orientation, your religion, your gender, or even just your hobbies. Being in the closet, feeling like you have to pretend all the time? It's fucking hard. Nobody does it because it's fun. But sometimes you have to, for safety's sake, keep your secrets secret. Magical Girl has experience with that. She knows how much it sucks, but can be necessary. She'll help you hold your secrets in your transformation locket, kept close so you never have to forget who you are.