Fear, approach anxiety or getting intimidated/spooked are just an illusion created by your mind.

When we are in danger, like for example, being chased by a dog, our mind tells our body to be in the fight-or-flight mode. This is a human instinct, so it is normal, fear helps us deal with this situation. We run faster as the dog chase us.

Same thing happens when we approach the girl we like. Our brain tells us to be in the fight-or-flight response mode. Your brain is now in fear, even if it's not really necessary. Overthinking about the girl being popular, high-valued, prettiest in the school/work, high status/rank, or "out of your league" would just add unnecessary fear, anxiety and stress to your brain.

You are not being chased by a dog, you aren't in a dangerous situation, so train your mind to be calm. Stop thinking about the results and physical factors that you have no control.