Fearing death doesn't mean being afraid of death.
Please look up the definitions of fear and afraid, then reconsider this statement.
Policemen and firefighters do everything they can to protect their lives in the face of danger, yet they gladly and willingly sacrifice their lives if it means saving innocents from harm.
Another broad generalization that is demonstrably false. There is even legal precedent
. Those accepted into the ranks of police and firefighting services span the full spectrum of humanity. And their reasons for choosing such careers are not uniformly altruistic. Granted, many such people have died for the sake of others—whether or not that was their intention. There are also many heroes who live to tell their tale (or not).
I'd be willing to bet that most heroes dive into action because they are unwilling to sit by and let the enemy or fate make bad things happen. They are not planning to "gladly and willingly sacrifice their lives." Gen. Patton said it best: "The object of war is not to die for your country but to make the other bastard die for his."