If you do not honour your words, no one else would.
Honour your words means treating what you say with respect and putting in sincere effort to achieve what you say. Being a leader would force you to think ahead and create a future. You may create a future that looks difficult. You may make promises that you don't know how to keep. And you may fail. However failure doesn't matter, as long as your intentions were honest and your efforts were sincere.
If you do not honour your words, no one else would. This is probably the most important criteria of being a leader.