Just because Google+ is shutting down on April 2nd doesn't mean your years of social posts will be lost in the void. The ArchiveTeam recently started caching public Google+ content to make it available on the Internet Archive after the fateful day. This won't include content that was deleted or made private before the archival process began, and might not include all comments or full-resolution media. Still, this will ensure that you have some way of reliving moments years down the road.
If you'd rather not have your activity recorded for posterity, you can either delete your Google+ account (if it's not too late) or else follow the Internet Archive's process for removing specific content.
It's not completely surprising that efforts would be underway to preserve Google+, but it's an unusual situation. You don't see archivists preserving a major social network (albeit one that struggled to compete) very often. The question is whether or not it will be a comprehensive record -- there isn't much time left to safeguard every last ounce of public content.