Sosie, the walking at the mall and at the gym with the folks you mention seems very companionable, pleasant....at my original work out place, which has since closed - it was a "women-only" and it was small, "close-knit" - they tried to start a Sat. morning walking club in Summer. It was around the neighborhood there. I did a few times and that was kinda nice. And it was nice to walk outside. I have never heard of Planet Fitness. Is it a big gym, like with pools and stuff?
I just tried the stair-climber <is that what it's called?> at my current club. It's good.