You mean like a type of affirmation?
Place the sentence somewhere you see it every day. Every day close your eyes and visualize what you want [example, say it's confidence, visualize yourself doing things confidently, like sitting tall, giving a presentation, getting an A+ on a test] when you feel satisfied with your ideal outcome say the line as if it's a fact [example 'I am a strong confident person'] then go out and try one thing that scares you, or make tiny shifts throughout your day you don't normally do [sit tall, raise your hand in class, say 'hi' to your crush]
Just like spells, the key is to visualize and believe it will work. If this is a chant, it's the same idea, you just might repeat the chant a few more times in one sitting.