I had a conversation with someone recently and their lament was they couldn't keep volunteers and certainly not "those Millennials." Of course I disagree, as I usually do
First if you are a volunteer manager, what are you doing to take care of your volunteers; remember a volunteer is not coming to do things with you for a check.
So what keeps them coming back?
Are you doing things to make their time comfortable? Like this Fire Department in Virginia?
Are you providing them with training ?
Are you providing them with time to connect with other volunteers?
Are you giving them meaningful experiences/ things to do that matter?
If you can't answer yes to these questions , then the next question is why do you have them?
Go take care of your volunteers