I have found that when I first begin meditating, it pays to explore my body for tension. I often seem to have tense facial muscles or shoulders. This is sometimes called "storing tension" there and sometimes such psychological sources of muscle tension are called "guarding". The reference is to tensing to avoid penetration into the body by a blow. If a soccer ball hits me in the belly, relaxed muscles will allow the force to penetrate deep into my gut but not if my 6-pack of abdominal muscles are tensed. Why not keep muscles tense all over all the time? Then, I would be protected, wouldn't I?
No, my muscles are not built to sustain tension indefinitely. Trying to do so lowers circulation, induces fatigue and no doubt, helps several other negatives. But modern life has difficulties and worries that are not sporadic, such as being chased by a tiger. Many difficulties such as worries about the future can cause muscular reaction that seems to go on and on.
As a child, Dr. Epstein had a stammer at times, especially when introducing himself or saying his own name. A therapist taught him to lightly stamp his foot or touch the table in front of him to distract his tension-producing mechanism and that strategy allowed him to speak without the anticipatory tension. Much of his adult practice has centered on situations where performance anxiety or inner predictions of possible pain or disappointment has caused patients to tense up and interfere with their own lives. Such holding tense or holding back can severely limit one's sex life or ability to give and receive love.
The best strategy for dealing with more subtle and persistent worries is often observation. Sitting still and focused on watching one's thoughts can allow a person a little space between the immediate worry and the person who is taking a step back and watching. That little space can permit a bit of distancing, a bit of self-compassion for the frightened and burdened person who is trying to deal with life. Sometimes, one evens gets a chuckle when one sees his mind at it again, producing the same images, fearing the same shadows.