Teddy Roosevelt listed some when he wrote: "The foes from whom we pray to be delivered are our own passions, appetites, and follies; and against these there is always need that we should war."
In this matter, we are all "career soldiers." Since this enemy is ever-present, we always need to be on guard. When a danger appears, we give the call to arms and leap into the breech. This enemy is poised to exploit our weaknesses, but we can arm ourselves and learn to fight (Ephesians 6:10-18).