My 39, Day 21.

Tipping is a very personal thing. It’s also not the time to be chintzy.

Other than a former boss who told me that she always tips – at worst two pennies for bad service so “they know I didn’t forget” – I’ve never had anyone share with me much thought about their tipping habits.

So my preferred practice has evolved over time, from the sweet freedom of a driver’s license at 16, dining out with friends, and quickly figuring out that 15 percent was the norm amongst my peers.

Driven by allowance, and in the college years, perceived necessities like Homecoming t-shirts and Zap photos, my tipping habits stayed in that realm well into my twenties.

I don’t think it was until I read a magazine article (one of those “10 Things Your So and So Isn’t Telling You” but wishes you knew pieces, and – lightbulb!

Fifteen percent is like entry level acceptable. Not at all appropriate for someone who went out of their way to make sure your experience was tops.

Cynical types will dismiss this as nothing more than self-serving greed. That’s how they make a living! Of course they want you to feel guilty not tipping them more!

Um, no.

While I’ve never hustled between kitchen and customer tables, I have slogged my way through enough service oriented jobs to know that whatever tip you leave them, they’ve darn well earned.

Whether in a restaurant or a hair place or a nail salon, I figured out over time that if I can’t afford to tack on 20 percent, I can’t afford to go.

The response to bad service is another matter, and one with no across the board solution.

I suppose your response depends largely on whether or not you ever plan to go back.

For me, and mine, once they are old enough to have conversations about such things, the rule of thumb will be to tip with generosity.

Not always easy, and not always convenient, but always the right thing to do.