An injector includes an injection needle and an activation button assembly operatively connected to the injection needle. The activation button assembly is translatable from an unactuated position to an actuated position, the actuated position being visually different than the unactuated position. A position of the activation button assembly between the unactuated position thereof and the actuated position thereof defines a threshold point, and movement of the activation button assembly beyond the threshold point secures the activation button assembly in the actuated position, and drives the injection needle from a retracted position thereof to an injection position thereof.