It seems like every time our piano tuner John comes to our house, he scolds me for waiting too long between tunings. I agree with him that it should be done every six months, but I don't really think about it until the piano sounds off-key.
The last time he came over, I was on the defensive. "If you would send out a postcard reminder like the dentist does every 6 months," I declared, "I would make sure to call you for an appointment in a timely fashion."
Without hesitating, he replied, "OK -- from now on, when the dentist sends you a postcard, call me."