Three quick tips to gain an instant charisma boost:
1. Lower the intonation of your voice at the end of your sentences.
2. Reduce how quickly and how often you nod.
3. Pause for two full seconds before you speak.
From this summary: https://github.com/benigeri/books/blob/master/The%20Charisma...
Those tips are in the introduction of the book so you can see if it works for you and decide if you want to continue reading the rest.
Personally, when I started doing only those 3 things, weird things happened that completely changed the behavior of other people towards me and then how I felt about other people. Worth a try.