If you've experienced a situation that demanded courage in your work, share your story. Fast Company will feature some of the best submissions online in the future. We would like your help identifying the most courageous leaders -- in business and elsewhere. Nominate candidates, and in the weeks to come, we'll put them to a vote.

In what situation did you show the most courage while on the job? What's the most difficult business decision you've ever had to make? When have you been called on to be brave under fire on behalf of your colleagues, your team, your company -- and your customers?