My objection is the word "MUST." Some can't and so forget it as as "must."
Each of us should stay as fit as reasonable, but to think everyone of us can fight off an attacker without a weapon or a lot of help is nonsense.
Ecclesiastes 12:13 *¶Let us hear the conclusion of the whole matter: Fear God, and keep his commandments: for this is the whole duty of man.
14 *For God shall bring every work into judgment, with every secret thing, whether it be good, or whether it be evil.