Most of them don't even realise they're lying, they just vastly overestimate and never check.  I estimated my runs were 5k:s, but when I finally checked on map it was only 3k. I adjusted and after having run a 5k regularly for a few weeks I can definitely see it's changing my body a bit. When she says "90 mins of cardio" it probably means waddling around a park for that time, stopping every now and then.