Let’s break down this sentence and remove some of the immediate emotion that it conjures up on those who utter it.
Will is a future tense word. If you could predict the future, you would likely be the richest person in the world. You can’t predict the future and it’s damn near impossible to predict what humans will do. Look at any crisis in modern history and the response of some people is baffling.
Who is they? Is it everyone? Probably not. Let’s focus on who they might be. It’s often people you don’t actually care about in general. Why are you choosing now to take in their opinion. Maybe it’s your family or friends. If this is something you want to do that doesn’t hurt anyone, shouldn’t they be rooting for you?
The sentence has think in it but didn’t you really mean that in the sense of judgement? Sure, you might not wanting to go streaking in public. You don’t want to break laws or social mores but usually this sentence is invoked before we embark on some personal journey of growth.
If you are hooked on this sentence, maybe reframe it as “What might they think?” Might has positive possibilities usually or it diminishes the negative. What if they might root for you? What if someone is looking to you for inspiration.
If you are hesitating on putting yourself out there, showing your talent, asking for help, or blazing a new trail ask your self, “Who might I be inspiring?”
