How many great ideas have been stopped in their tracks because the person who could implement them was discouraged?
How many have you, personally, kept from coming into the world by discouraging someone? How about times you’ve discouraged yourself?
How do you tell the difference between being unnecessarily discouraging and being helpfully realistic?
It’s an awfully thin line to walk. Be honest, but remember you may be wrong. You can disagree and still be supportive.