Once you can stay with a least a few cycles, let the breath recede into the background and choose your anxiety sensations as a primary object of attention. Feel how they manifest in the muscle tension, restlessness, and so forth. Try to approach these sensations with an attitude of interest and curiosity – not asking what they mean or where they come from, but just investigating how they feel in each instant. See if the sensations are solid or perhaps subtly changing from moment to moment. As you’ve done before, whenever your mind begins to wander away from the sensations, gently bring it back.
Notice also, any urges to withdraw from the anxiety sensations – to get up, shift position, or make them stop. The key here is to stay with what is happening in the body rather than trying to make the sensations stop or go away.