Because of the ceaseless conflict with Satan (and our own fleshly nature), it is our responsibility to stay grounded on the foundation which Christ has laid for us. Are we looking to Him to be the source of our strength or are we relying on our own power? Are we determining daily to stand firm against Satan's schemes, or do we cave to convenience?
"The only easy day was yesterday." - US Navy Seals.
When a soldier prepares for battle, he or she "suits up." They go through a process (usually the same process they've established each time) of putting each piece of gear in place---Undershirt, uniform shirt, pants, duty belt/gear belt, boots, bullet-proof vest, ammunition, helmet, and weapon(s). This process of preparation is vital, as each battle brings different challenges. A soldier must be in constant readiness.