Yeah but it depends how mundane, it's normal don't worry

I mean small talk levels of mundane. I get exhausted just thinking about talking to people and I just sat through a two hour lecture of why I need to make more small talk and now I want to lay down and drink gas.

Does it make you anxious? talking? Cause that's mentally exhausting, thinking about what worries you

I was an introvert for a long time. I got Socially tired. Socializing with people, small groups or large crowds, made me very tired. It’s more common than you’d think.

No, I just don't like opening my mouth

Well, everyone feels it differently.

It could be something completely different like low iron levels in the blood, that makes you really lethargic very quickly