As taken from Volunteer Canada:

When you volunteer, you give part of yourself–your time, energy, skills and feelings. You give to your family and friends, to your
neighbours, to your community. Sometimes, you are giving to people you don’t know, to people thousands of miles away.

Giving is one of the reasons why people volunteer. Their contributions to others and to their communities bring them feelings of self-fulfillment and the knowledge that they have made a difference.