Mr. .357. Don't leave home without it. Learn how to use it. Get a concealed carry permit. Have it with you in your car and in your office.
Prepare yourself mentally to understand that what happens in the first 10 seconds will determine whether you, and your co-workers/family/friends live or die. Understand that if you do not act quickly and decisively, you and they will certainly die. Ask forgiveness of your Savior and remember the heros on flight 93.
Just remember...better to be judged by twelve than carried by six.