I’m 21, and I consider myself an adult.
I have commitments and responsibilities to take of, and volunteering will be the last on the list of stuff to do.
I would volunteer if:
A. I have more time on my hands.
B. I’m willing to.
C. It’s relevant to my interest.
Volunteer is not a life’s responsibility unless it’s a requirement for certain things.
So if you want people to volunteer for certain causes and projects, then it’s best if you entice and attract them instead of insults and intimidation.