If you are a leader of a group, of almost any sort, one of your key responsibilities is morale. The effectiveness and longevity of the group (whatever its purpose) is hugely affected by the collective attitude. And whether you like it or not, your attitude affects that collective.
It is terribly, terribly easy for you to damage group morale, even with the best of intentions. For instance, you may well find yourself uncertain about whether you are leading the group in a good direction -- that sort of self-doubt is usually quite healthy. But for heaven's sake, don't *show* it. When you are telling the members of the group where it's all going, you have to *sell* that, just as much as if you were selling to a consumer. Don't stammer, don't hesitate, don't let that uncertainty bubble up -- go at it with vigor and overt self-confidence. Even when opening up the question of whether it's the right direction, do so with confidence: discuss the questions openly, make a decision, and then close the matter.
This doesn't mean lying to the group, but it *does* mean paying attention to your own style and how it affects others. Think about it from the group member's point of view. If you were following someone who seemed unsure whether this was the right thing to do or not, would you be likely to throw yourself into it 100%? Keep in mind that groups mostly succeed precisely because people are passionate about them and about what they are doing. So if you sap that passion, you're damaging the project.
Yes, it's hard work. It means putting on your "game face" when you are interacting with the group. It means throwing *yourself* at the project 120%, your doubts aside, to get everyone else to go 100%. No one ever said leadership was easy...