I live in a housing development on a private lake in Frisco, Texas. A problem we are having is people and children from neighboring developments have no concept of the meaning of "PRIVATE". 

For some reason, because the lake it there. these "outsiders" think they can just walk across my front and rear yards to reach the "private" lake.

There is a sidewalk completely around the lake, just a couple of feet from the edge of the lake. Same size as a public sidewalk. But int is a PRIVATE sidewalk. 

My personal property extends to within 10 feet of this sidewalk. I have no fencing to keep trespassers out of my yard or wandering up to my back porch. About 75 feet from the sidewalk.

Only homeowners in the HOA have access rights to the sidewalk around the lake. They can legally take a walk around the lake. But that doesn't grant them or anyone rights to wander up onto my property.

After 25 years of residence I am forced to post "NO TRESPASSING" signs and am considering blocking lake access around my house with steel fencing.

Society has changed. And it is forcing me to change my belief that people want to do the right thing and live a life of good morals and respect of other people. Today is seems one's self wants are all that matters. The world be damned.