Imagine having a transparent door. Nothing to hide, no fear from breaking in, no separation from 'in' or 'out'.
Do you think you have to be brave to have a door like this? I think so.
Imagine that that kind of door is the door to your heart... Transparent, clear, 'open'. What a brave heart you have to have to show it to the whole world! Not many people can do that.
I think there's still a way to be brave when we are not brave enough to choose a transparent door. We can decide to have an inviting door and when people knock on our door, we can let them in or not.
Choose the door that represents you - big, small, wide, decorated, painted, vintage... The door will invite people who have the same feelings, the same expectations, the same values. It will be easier to decide to let them in or not when they knock on your door. (Of course, practicing to let everyone in would be the best thing to do, but for a start, this is one way to practice bravery).
Free yourself from fear! And be creative on a search for the door that fit you the most.