Our brains haven't evolved as quickly as the world around us. It still operates as though our lives could be threatened at any second. That's why we have the fight or flight response. It's designed to keep us safe from danger. However, most of us aren't in situations very often that trigger the need for fight or flight.
But there's another primitive response your brain can have. Freeze. It's still your brain trying to protect you from what it perceives as danger, just like fight or flight. And it's one you probably have much more frequently. It doesn't necessarily mean your whole body freezes, just that you don't move forward with a plan or a change.
This can look like...