Crouch down and guide your finger into the vagina. Then tense your pelvic floor muscle and feel the pressure on your finger. Then relax the muscle and tense it again.
Place a finger on your perineum while lying on your back. Then tense your pelvic floor muscle until the tip of your finger has been drawn into your vagina and relax it again in short intervals.
For added effect, do this on your coffee break.
