This might not always be easy, but take those things on by doing some rational investigation and assessment or evaluation one-at-a-time. For example:

Would it actually be possible for something or someone to even get behind a shower curtain without being seen? Can the mirrors actually be used for watching for things rather than trying to avoid them? Can you add a bit of song-and-dance as you work to occupy your senses with something other than silence or creaking pipes or whatever? Is your trash dumpster actually too smelly for people to be hanging around it? In other words, find ways to occupy your mind along the line of security rather than fear.