The whole group learns to work on shared problems

Joining a group is useful because it provides opportunities to learn with and from other people, to understand one's own patterns of thought and behavior and those of others, and to perceive how group members react to one another.  We live and interact with people everyday.  Often there are things that other people are experiencing or grappling with that can be beneficial to share with others.  In group therapy, you learn that perhaps you're not as different as you think or that you're not alone.  You'll meet and engage with other people, and the whole group learns to work on shared problems- one of the most beneficial aspects.  The more you involve yourself in the group, the more you get out of it.