How do you level up mental state

[Finnegan16 0]

I’ve been trying to up all of my skills, and have maxed stamina driving and swimming, shooting and punching are prob next, but what about mental state? I’ve been playing for about a month and have hit the max many times and lived, but it’s not seeing to go up, so how do you level it up? Do I just need to grind it more or is there another way?

[Finnegan16 0]

May be a little bit before I can see responses, but thank you so much if you did (also not sure if this will send)

[Finnegan16 0]

Just checked the wiki, and it seems that the “skill” is just your warning bar, my bad lol