It is achieved by being Physically Strong, Mentally Awake, and Morally Straight.

It also means that you are always in a state of readiness in mind and body to do your duty.

Be Prepared in Mind: It can be achieved by having disciplined yourself to be obedient to every order, and also by having thought out beforehand any accident or situation that might occur, so that you know the right thing to do at the right moment, and are willing to do it.

Be prepared in Body: It can be achieved by making yourself string active and able to do the right things at the tight moment, and do it.