After addressing the situation take a walk. Walking will clear your head and allow you to think about the severity of what is going on with your emotions and within the company. Are your assumptions and fears right? Can you really not stand THAT person? A little perspective can go a long way before a call to action is required.
Negativity also stems from feeling rejected or experiencing anger. Perhaps you pitched a proposal to a client or boss that was shot down. You might feel negative because you feel rejected. Or, maybe an undeserving competitor or coworker got what was to be your account. You might feel very angry and also negative. Regardless as to what happened, immediate reactions can be detrimental to your reputation. Don't let feeling negative ruin your reputation.
Twenty percent of your work generally produces 80 percent of your results! You need to stay focused and, again, gain perspective on your feelings and why you feel that way. If you need to take an hour to walk it off, or a mental health day- do so! Whatever you do, don't react when feeling fueled with negative feelings- it will only escalate a situation.
Stay as positive as possible and remember to focus on the 20% of work that produces 80% of results. Keep your eye on the prize!