To defend yourself, you have to be aware of what is going on around you. You shouldn't be walking around absentmindedly daydreaming. But even if you are, at some point it may become necessary to defend yourself (hopefully not, but one always needs to be prepared). Part of that preparation involves the physical skills you can learn here at the Shuyokan Martial Arts Center. Another part is being aware of what is going on around you and then reacting to how the situation changes, either independent of you and your actions, or because of you and your actions.
One method (or system) of reacting to change is known as the OODA Loop (observe–orient–decide–act) and was developed by military strategist and United States Air Force Colonel John Boyd. Boyd applied the concept to the combat operations process, often at the operational level during military campaigns.
But the process isn't centered on you and you alone. There are two people (at a minimum) involved in all self-defense situations. Yes, you should go through the process of Observing, Orienting, Deciding and Acting, but not simply to decide when to make your move. The real goal is to keep your opponent continually in the OODA Loop (reacting to what you are doing) while you determine the precise moment to exit the loop and either leave the area or perform a self-defense technique to end the situation.
Even if your first technique does not end the situation, your opponent will be forced to react to what you just did and just like that, he (or she) is back in the OODA Loop.
Credit: Patrick Edwin Moran, CC BY 3.0, via Wikimedia Commons