"Few people were on a ship, which got lost at sea, due to a tide.
One of them, a pessimist kept telling everyone that the ship would sink today... there was another guy, an optimist, who kept telling that they would reach the shore today...
Days passed and nothing happened.
Fellow passengers got bugged and threw-out the pessimist saying "You always give us the bad news" and after few days, they threw-out the optimist saying "we are frustrated, what you say, never happens".
It pays to be realistically optimist.
Don't get carried away just by the audience, your confidence or the content.
Be realistic about everything and be open to change anything all points in time, it may be speaking or writing.