Your Amygdala is a part of you that wants your attention. Its the brain's "smoke" detector, and it is the key structure that activates your body's alert response to stress, coordinated by your sympathetic nervous system, commonly called "fight or flight". If you've been dealing with high stress for any period of time- short or long, that detector has been making noise.
How do I reset the smoke detector?
Your biological system is constantly scanning your environment, assessing "how safe is this?". If your alarm is going off in the absence of an external threat, then it is likely reacting to something it has coded as an internally generated threat signal, and it won't allow deactivation. The reaction is "where's the fire"- and we try to find the source of threat. Usually we will find something in the environment to project our sense of threat onto.
However if you can can allow your attention to go out into the environment and simply see what you see, hear what you hear, smell what you smell, etc; allowing your senses to take in the actual experience, then your attention is going to a different brain department - the part responsible for orientation.
The result is that it comes out of the loop of "hey there's something wrong here and I have to figure out what it is" and it lets your system of neuroception do its job- to assess the safety of the current moment, and suddenly you feel more safe. This felt sense of safety initiates and helps sustain a physiological phase of relaxation and also human connection.