Remaining in a specific vibrational frequency refers to not changing how you feel at any given moment, because your feelings are what dictate your inner energy ... the frequency at which your being as a whole is vibrating.
So of course what has to be changed is how you feel, if you want to get to another level of vibrational frequency. And you change how you feel, by moving your thoughts into another direction, another direction where you have a greater chance of feeling better.
This is a topic that a great many of my posts keep hammering on about, because it is so important: if you can learn this, can figure out how to apply it to your life, you will create many important changes to the state of your well being. Think of it as changing direction 180 degrees from the worried or painful place in which you find yourself, to the place of greater good feeling where you could be.
You might like to bring up a joyous memory, or you might like to think about something you are trying to bring about in your life, the completion of which would bring a state of good feeling and satisfaction to you, and as you consider this scenario, your feelings of worry and pain subside. From that better vibrational place you will be able to make much better decisions about your worry or your pain, simply because you will be in a better place.
Apply this always and watch the changes.
Image: Monument Valley, Arizona