I can think of a couple of mums from the school run who have that kind of figure, there are a few who are just naturally tall and willowluy/slim, and even after havcign kids have retained that shape. A couple of them go running/work put at the gym etc, some are just the type that dont seem to need to exercise but stay slim.
I am never going to be that slim, big boobs, wide hips, but small waist, very hourglass figure, when I exercise I am fairly petite, bit not slim, I need to lsoe 10lb at the moment but dotn have the motivation... Tbh tho given I have five kids I a pretty happy with my figure.
Kudos to those who make the time to exercise, I always feel better when I do I just lack the motivation to do it consistently.,.eyes up running kit that has been little used since my 10k in the summer...