First person camera vignette, how to increase/decrease intensity dynamically?

I’m trying to create this effect to make the player look more tired the more they run. How do i make the vignette intensity value go higher the lower the player’s stamina? I have a float for current stamina but i’m not sure where to start with this. Please help!

You can get at it from the player camera like this:

Okay, though I don’t know how to scale the intensity smoothly from 0 to 1 as the stamina drops from say 100 to 0. How do i make the intensity value the inverse of the stamina value?

Wow, it works perfectly! Thank you for your help!