And you just thought it just taught people about romance. How a movie can be its own mini-MBA.

People often ask me how my undergraduate education or law degree helped me in starting a company. But the truth is I learned more about business from When Harry Met Sally, which is marking its 25-year anniversary this year.

Here are my top three When Harry Met Sally business success lessons:

1. Take your customers to the airport as long as you can.

Harry: You take someone to the airport, it’ clearly the beginning of the relationship. That’s why I have never taken anyone to the airport at the beginning of a relationship.
Sally: Why?
Harry: Because eventually things move on, and you don’t take someone to the airport, and I never wanted anyone to say to me, “How come you never take me to the airport anymore?”
Sally: It’s amazing. You look like a normal person, but actually you are the angel of death.

I’m a huge fan of driving to the airport as long as possible–for customers. There’s no reason to do less than you should before you absolutely have to. To me, this means writing handwritten cards to customers, calling them, meeting with them, talking with them face to face. Our first year after launching the Julep beauty subscription program, called Maven, I handwrote anniversary letters to every subscriber, tailoring notes with personalized messages based on where they lived, or what products they ordered. I’m grateful that we have too many Mavens for me to do that today, but I’m glad I did it when I could–because it set the foundation and culture for the kind of company Julep is today. Earning customer loyalty starts with being thoughtful about one person: your first customer. Then, maintain as strong a connection with your first customer–and all the ones that come along after–for as long as you possibly can.

2. There is a Sally inside of every customer.

Harry: There are two kinds of women: high maintenance and low maintenance.
Sally: Which one am I?
Harry: You’re the worst kind. You’re high maintenance, but you think you’re low maintenance.
Sally: I don’t see that.
Harry: You don’t see that? “Waiter, I’ll begin with a house salad, but I don’t want the regular dressing. I’ll have the balsamic vinegar and oil, but on the side. And then the salmon with the mustard sauce, but I want the mustard sauce on the side.” “On the side” is a very big thing for you.
Sally: Well, I just want it the way I want it.
Harry: I know: high maintenance.

Most customers are just like Sally; they are high maintenance but think they are low maintenance. Being successful in business requires entrepreneurs to find the joy in connecting to the Sallys of the world, just like Harry ultimately did. You have to expect your customers will “want it the way they want it,” ask for more and more things “on the side”, and reject one-size-fits-all approaches to marketing and product design. Serving up uniform offerings is the same thing as having a one-sided conversation where you don’t listen to what the other person is saying. If you are lucky enough to have customers like Sally who can clearly articulate what they want, give them what they want and then some. For example, at Julep, we have always enabled our Mavens to swap their monthly boxes into another “style profile,” and to add products onto their boxes. We are now taking the next logical step of enabling true customization of our monthly subscription box. We want Sally to have exactly what she wants, and not have to pay for anything she doesn’t.

3. Don’t wait to act on something you know already.

Marie: I don’t think he’s every going to leave her.
Sally: I know he’s never going to leave her.
Marie: You’re right, you’re right. I know you’re right.

As busy entrepreneurs, we often wait to act on decisions we know deep down to be right–especially where another human being is concerned. We hope the situation will change, that an uncooperative employee will somehow learn to collaborate, or that a careless employee will learn to be more careful. Don’t be Marie! If you find yourself repeatedly coming back to the same issue, saying to your colleagues or to yourself, “You’re right, you’re right. I know you’re right,”–then take action! Don’t wait three-quarters of the movie to take the step that you (and everyone else) knows is right for your business. That may mean letting a colleague go, or ending a partnership that’s not working out. It will be worth it to do the right thing.

Running a business is a complex, all-encompassing, crazy experience, but it’s also great fun. If you want to pay for an MBA, go for it, but you can learn a lot by watching movies.