It seems sort of obvious, but I love that it’s nicely underlined in two separate books that I read today: You truly connect to the Force by letting go of the noise of your own thoughts. You hear the Force helping you through calm and quiet.
There are plenty of examples of using the Force through intense emotions, pretty much every dark sider has done this, and it’s usually through anger and fear and, ultimately, it usually brings suffering. Dark siders are not happy people, they have pretty much nothing but their own pain, they feel very little true joy. That kind of thing lingers, whether in their kyber crystal/the blade of their lightsaber (as Kanan tells us in Star Wars: Rebels) or because Force-sensitive people are psychic and so those thoughts/feelings linger in them and the air around them.
But when you want to use the Force in balance, when it’s in harmony with the connective web of energy that binds all things everywhere, life and death, you reach out to it through calm.
The Force helps you when you let go of the swirling static of your own mental noise and instead focus on the tide of the galaxy around you. If you have a dozen things yelling in your head, you miss the little details of what the Force is trying to tell you. If a dozen other people around you are all pouring that fear or hate or rage into the Force, it makes it harder to see those little details that can be so important, that you’d miss because of that noise. That it can get bad enough, as Mace says in Attack of the Clones, that it keeps others from using it. That enough selfishness and greed and cruelty being poured into the Force, can have a galaxy-wide effect.
If everyone is shouting, you can’t hear the Force’s whisper.
It’s when Rey lets go of her panic, when she lets go of her confusion, that is when the Force comes whispering to her, lets her see things that she needs to see.