Contrary to the belief that it takes a large number of people to build a great company or to do a great deed, you do not need a large crowd to do any great deed. You just need a few passionate people. More few than you think will do.
Leading people is a difficult thing. Just having two people agree to do a thing is a big deal, talk less of a large crowd. To pursue a goal or a mission, the people with you have to be at the same level of understanding of what the mission is about, anyone who doesn't understand enough is a burden and will pull the team back.
Commitment is another thing. Everyone will have varying levels of commitments, and for a large crowd, it will vary by a whole lot. This prevents anything from getting done, because those that are expected to do it can always have one excuse or the other to justify their inaction.
What you need is a few people. Very few people in order to pursue and achieve a mission. So what do you do with the crowd? Raise the standard of your organization's principles. Raise the standard and watch them drop like flies. People who aren't meant for a task will immediately excuse themselves from it whenever things get tough.
Now you have very few, committed and passionate individuals, you can pursue your goals.
Here are metrics for things that get done:
What gets accounted for gets done.
What gets expected gets done.
What gets inspected gets done.
What gets measured gets done.
What gets appreciated/rewarded gets done.
Measure your plans and actions, account for every single thing to do done, let it be known what is expected, inspect what is expected to be sure its done, measure everything and reward everything.