I like to start listing the things I'm grateful for, and it's even better if I can write them down. It helps me focus on the positive things around me, instead of my anxious thoughts.
One of my friends consciously focuses on the feeling of her feet on the floor, her back in her chair, and her hands on her lap to bring her back to the present.
It could also be taking several long, deep breaths. Or doing a few yoga poses. Things like that.