How do you actually die less?

I know the drill, position better, track key cooldowns, I know all the theory, but how do you actually force yourself to do this?

Like, who doesn't know that an adc shouldn't go alone close to gragas? I for sure know it, and yet I still do it. I know I should wait for samira to use E before attacking, and yet I go attack her anyway. I know that no matter how fed I am, I am not winning a 1v2 against their botlane, but I still try anyway.

I can't apply these knowledge during games and instead I always get caught, or walk in unsafe spots.