How do I start a sentence about growth mindset but without start with I will tell you about and ext?

As with every essay topic: You don't. Your introduction is supposed to pique the reader's interest. They don't care for stock phrases & scientific jargon, they want to know why they should waste the next 30 seconds glancing over some random composition.
So give it to 'em. Think of a way to connect the phrase with real life.