If you watched Sex and the City you'll be familiar with Samantha Jones singing the praises of Kegel exercises.
If you didn't, here's your chance to catch up: for women, repeatedly contracting and relaxing your pelvic floor muscles supposedly helps you orgasm more easily, and is good for incontinence issues post childbirth.
For men, there's evidence strengthening your Kegel muscles can help with erectile dysfunction.
All in all, they're not a bad thing to get into.
And because we basically live in the future, there is of course an app for that.
British start up Chiaro is selling a device called Elvie, a Bluetooth-enabled egg that is inserted into the vagina and tracks the strength of Kegel muscle contractions through motion sensors.
Your "most personal" trainer includes five-minute tracked exercises to check whether you're clenching efficiently and a game where you have to keep a ball bouncing by contracting and releasing in time.
As Samantha was keen to point out, you can do the exercises anywhere, sitting or standing - but at £150 a pop, you better hope that pulling the faces in the promotional video below is worth it: