Holding a loaded gun to my head

It finally feels like I'm in control, so close to ending it. From what I've learnt in medschool I should aim at the brain stem.

I have no reason to live but it's still so hard to pull the trigger. Some fucking instinct keeps telling me not to do it. Maybe if I get really high on opioids or amphetamines I could do it. Amphetamines might be better but I don't have them at my disposal right now.