A clear role can turn unused enthusiasm into a useful contribution.

Willingness without a job attached tends to evaporate. Someone turns up keen, hovers for twenty minutes, cannot see where to put themselves, and quietly decides they are in the way, which is how groups lose the people they most needed. It is rarely a lack of commitment. It is a missing sentence describing what exactly is theirs to do.

When somebody offers to help, give them one specific thing with a beginning and an end. Say who else is involved and when it needs to be done. If you are the eager one, ask for a defined task rather than waiting to be spotted.