Vitality improves your chances of surviving a wound by decreasing the possibility of bleeding and instant death through critical damage of a body part.
Vitality can easily be raised by running through a fire to take damage. Be careful not to stay too long in the fire because of the high damage it causes. You can use eTG-change regenerative stimulant injector and Propital regenerative stimulant injector to heal yourself
A safer option to raise vitality is to obtain a heavy bleed and use Propital regenerative stimulant injector to heal yourself without fixing the heavy bleed.You can also use barbed wire with it's lower damage output and combine these two options.