There is perhaps nothing more important in life than our being able to recognize when we have experienced a physical sensation driven by a subconscious conclusion. If you don't know how to do this, it is a skill that you must learn. And it is one that is implict in your ability to meet the basic requirements of being an adult.
There are reasons why we might be sensation oblivious. A typical scenario is that we are constantly active and, therefore, always using some aspect of our body, so it is hard to notice a change in one area. For people in this situation, we recommen the occasional check-in. It can take less than a minute but essentially includes your taking a break. Sitting down or standing still. Seeing if you can relax all areas of your body and put yourself in a stasis of sorts.
Another scenario is the person who is constantly engaged. As opposed to the physical example above, this is a more sedate state from a body standpoint but more involved from a mental capacity. A person in a call center, a retail clerk, a taxi driver, etc. In all cases the job may not be physically demanding but you are always interacting with someone or on alert in case you need to do something.
A final scenario is the contentious person. A person working in the emergency room comes to mind. Or perhaps someone in any number of law enforcement situations. Again, your mind is regularly going and often in pressure situations, so it may be hard to recognize what you are feeling inside.
Regardless of what your daily routine might include, you must find pout ways to recognize when something changes inside. It may be your heart racing for no good reason, an uptick in your discomfort, a change in your voice, or a noticeable temperament change. Whatever it may be, it is important to know when your brain is thinking "attack" and that response does not make sense for where you are at.