As Goop points out, the pelvic floor is a group of muscles at the bottom of the pelvis that, when strengthened, allow you to have "proper control" over your bladder and bowels.
"Try peeing in the shower squatting down," the article suggests, complete with a diagram. "'When you squat to pee as opposed to sitting up straight on the toilet, you automatically engage your pelvic floor and it naturally stretches and tones."
The article goes on to further explain how to use the bathroom correctly.
"Because your urethra is pointed straight down in this position all you have to do is relax for urine to flow out easily - as opposed to sitting up straight and having to strain to empty your bladder," Goop advises. "It's important to activate the muscles that you use [to] cut your pee off mid-stream,' it says. 'To do this, contract, pull up, and hold."