Overwhelm is a state of mind. Balancing a lot of competing priorities is part of the job description of most leaders, and you're likely no exception. Responding in "panic mode," however, isn't required.
It isn't even a good idea.
Your team learns, from you, how to respond to pressure. If you're panicking, they are likely to do so, too. Instead, find your center. Take a meditation course -- or a little bit of Mindfulness-Based Stress Reduction (MBSR) -- and learn how to center yourself no matter what is going on around you. (I knew I had this down when I learned how to lower my blood pressure right before the doctor put the cuff on me!)
A quick cheat on this: take 3 very deep breaths, slowly. Breathe to the bottom of your lungs. You'll know you've done it when, as you inhale, your stomach pushes OUT. (When you exhale one of these breaths, your stomach goes flatter. Yes, that's the opposite of inhaling and pulling in your abs!)
It's never productive to visibly give in to your agitation and fear on the job. If you're scared, tell a spouse or trusted friend, but remember that, to your team, you're Typhoid Mary (or Michael), infecting each of them with whatever mood you display.
