My cats are harness trained. I take them out in their fenced yard but I do not leave them out there unsupervised. I stay with them. And when I tell them it's time to come in, they run to the door and stand in line and wait for me to take their harnesses off.

However, if they didn't have a little yard I know they would still be perfectly happy as indoor cats, because up until 7 years ago my cats did not have a yard and weren't harness trained and were happy and healthy and safe.

Plenty of attention from their human, including daily grooming and daily interactive games for exercise, a cat tree, a sunny window...they don't need to "run free".

I couldn't bear the worry of not knowing where they are and that they are safe and healthy, every minute of the day.