My first introduction to group nudity was when I was 16.

I had become interested in joining a pagan group that often met in the local woods.

So upon contacting them many times, I was invited along to join them. I was told that the initiation was done skyclad. Which means naked. 

As a young man I was nervous about others seeing me naked and of course had the typical male worry.

But the day arrived and I decided just to go with it.  In the woods there were a patch of grass among the trees here I saw people's clothing and it was here I timidly stripped off. I could hear voices from the trees  and once naked I walked towards the others.  There where many people there men and woman both naked sitting around the fire.
They welcomed me and I sat with them chatting for a while. 

That day I felt connected to mother earth and when ever I am naked I feel this way.  It is the natural state to be in.