I share Sisabel's methods. I also use a couple in-the-moment physiological techniques if I sense my anxiety spiking, particularly at work. My favorite is something I picked up from Queer Eye (bless) called "alternate nostril breathing." You can read the details here, but the basic process is:

1. Gently place your index and middle fingertips between your eyebrows so that your pinkie and ring finger can rest on your left nostril, and your thumb can rest on your right.
2. Close your right nostril using your thumb and exhale through your left nostril, then inhale through the same nostril.
3. Switch sides, closing your left nostril with your pinkie and ring fingers so you can exhale and inhale again through your right nostril.
4. Continue alternating (exhale-inhale left, exhale-inhale right) for a few minutes, or until you feel more relaxed.

I can discretely do this at my desk at work, and it forces me to be deliberate about and attentive to my breathing, while distracting me from my worried thoughts. My heart rate comes down, and my whole body relaxes a little. This makes it so much easier for me to proceed to other longer-term coping methods, like meditating. I find it easier to rationalize some of my more extreme anxiety thoughts once I've calmed down like this as well.

Good luck, and much love!