Anxiety attacks often begin with racing negative thoughts and shortness of breath, for some this can escalate and be debilitating. Although medical opinion is divided on the effectiveness on breathing techniques, given that one can be performed in less than a minute, it may be worth trying.
I’d suggest that they can be effective for two reasons. Firstly, counting whilst breathing distracts the mind from anxious thoughts, providing a circuit breaker on the downward spiral of catastrophe. Secondly, they negate the shallow breathing that occurs during an attack.