How do you change your thoughts?

I’m struggling a bit with how to change my thoughts.

Unintentional model:
C – Being on camera
T – I don’t express myself well
F – Insecure
A – Acting like I’m insecure
R – Being perceived as insecure

Intentional model:
C – Being on camera
T – It’s no big deal
F – Relaxed
A – Act more natural
R – People will see the real me

How do I go from being really uncomfortable on camera (there are more than one thought about why I look and sound strange on camera as well, all related to how I’m perceived by those who will watch the video) to being at ease with it? I do feel like it’s not such a big deal and still I feel so insecure about it so clearly this is overriding. Where do I start? Is this step too big for me?