Being on stage gives you a power that you may not be aware of.
Feel how much you respect the speaker when you are in an audience. You probably heckle them very rarely, maybe you've never ever heckled in your life!
This respect is due not only to the personality of the speaker, but also to his social status: yes, being on stage is a social status in its own right and you get power from it!
When walking towards the stage, you can imagine you're wearing garments meaning high rank such as a military jacket with golden stripes, or that you've got a good many feathers on your head if you're more inclined to value native american traditions than the local army. Wear a papal tiara if such is your choice, feel a cloak falling down from you shoulders in your back... Just find what works for you, in accord with your own social values. Even the stick of a pilgrim can do. Conjure up the feeling of power or sacredness that you can get from wearing such clothing or holding such stick. Being the speaker gives you that, so handle it!
If this scares you... add a drop of humility. Don't identify. It's not you, it's not the ego, it's just a role, a social role to play. So hold your own, feel the fear and do it anyway! You will be respected.