I feel like the truest forms of self expression have to come from things you find a genuine interest in. A lot of the time people express themselves through a creative outlet like fashion, scrapbooking, coloring (my personal favorite hehe), design, etc. I think it’s important to acknowledge what you’re passionate about and engage in it in whatever form that may take. It may also help to explore all kinds of hobbies, just have fun with it.
