If you don't have the social enhancer in your current playthrough when reaching the part where you have to withhold and talk to
Doctor Isaias Sandoval
from suicide, then these conversation options in order:
*** Spoiler - click to reveal ***1 - Tough Love
2 - Tough Love
3 - Inspire
This might or might not work, it all depends on the previous choices you made on certain events.
This will make Doctor Isaias Sandoval reconsider his suicide attempt, and hand over the gun, the achievement would pop up after regaining control of your character.