I have little tolerance for the easily discouraged; those sad souls who wander in wringing their hands and describing a minor barrier they've encountered.
Life is filled with barriers. Frequently, their excuse is akin to proclaiming that there are traffic jams, rain is on the way or the copier is broken.
So you encountered a barrier. Find a way around, over, under or through it. Unless those options are stymied, it is simply a temporary delay.
Team members who mention significant problems and then energetically work to resolve them are gems. So too are those who have the courage to note serious problems that might block the entire project but who do so with a genuine dedication to the mission. The ones who trip over pebbles, of course, are beyond frustrating.
One of the most dangerous types, however, is the nay-believer who is not a nay-sayer. These sly operators believe that the difficulties are insurmountable but never voice their concerns. That group can become unknowing saboteurs since their defeatist mentality may hinder the vigorous execution that is needed for success. Their unspoken mantra is "We'll never win" and the resulting behavior can be a morale-killer.
I suspect their attitude inspired the slogan, "Lead, Follow, or Get Out of the Way."