If your project has no goals or measurable benchmarks, your volunteers will lose steam quickly.  For best results set goals that are specific, measurable, achievable, realistic and timely.  Let people know exactly what is expected and watch them rise to the occasion.

Sometimes repetitive tasks can get a little bit boring.  Here's where you get to be creative and make it fun!  Create a way to measure and track progress in an exciting way.  If you're using the Map App, this is built in.  Seeing how quickly a group can clear dots/markers is a simple way to make it past the finish line.

If you set good goals to begin with, this is a natural and easy step to impliment at the end.  Whether or not your group moves on to a new project or not, share something special with them to let them know how valued their time and efforts have been.  It can be anything from a simple thank you note to a full out pizza party.