Muhammad Yunus just had a milestone birthday. On June 28, he turned 75. It's a big moment for a man who's had many big moments in his life — most notably the 2006 Nobel Peace Prize for founding , which loans small sums, aka "microcredit," to the poor, mainly women, so they can start their own businesses.

Yunus stopped by NPR last week — he was in Washington, D.C., for a conference — wearing the long, open-necked "kurta" shirt of his native Bangladesh. "[A tie] looks funny on me," he joked.

He spoke with us about how to spend senior years (spoiler alert: he's anti-retirement) and why he thinks small loans can make a huge difference in the lives of the poor.

You're at an age when many people are retired. But you're still a busy man. Even though you no longer run the Grameen Bank, you're chairman of the , which promotes businesses that aim to solve the world's problems, and you're speaking on panels.

The word 'retirement' is a very harmful word because it tells you that you have no more use left in you. You retire a ship, you have no use for it, you just put it in mothballs.

A human being is not something you can mothball.

Are you enjoying your older years?

For the first [stage of your life, you are] busy growing up, getting married, raising children, working, always trying to fill responsibilities, always under pressure. Now in the second stage, for the first time, I am free. I do whatever I want to do. I want to make my dreams and wishes true. And I do whatever I enjoy.

What about discounts for senior citizens. Are you pro or con?

I am as good as anyone else. Why should I have a discount? You are treating me differently.

You won the Nobel Prize for the many small loans that your bank gives to poor people. That was a revolutionary idea.

The banking system is designed for rich people. So you don't have any room for the poor people to get in there. The welfare system throws them a few crumbs, but that's it.

Credit is a human right. You have the right to food, shelter, to work. You can create your own work with the money you get.

I can only imagine how intimidating it would be for a poor person to walk into a big bank and ask for a loan.

Going into a bank should be just like when you shop. You don't need courage to buy groceries.

And someone can borrow money from the bank you founded, Grameen Bank, without any collateral?

In microcredit, we are not asking for any collateral. Anybody's entitled. We're not asking what you've got. We're asking what you need.

What would a woman in Bangladesh ask for?

She'll say, I'll think, about $30. She cannot even imagine $100.

And most loans are ... ?

Something like $100 or $150.

The idea is the money will go to start a business.

You have to have a business idea. For example, in Bangladesh, a lot of women propose agriculture-related business: growing something, selling something, producing something.

The bank also has a U.S. offshoot — . Are you surprised by the kinds of businesses American women are starting up?

In Bangladesh, our women don't do hairdressing for money; they do the hair for each other. But in the United States, this is a business, so they set up in a shop to do the hairdressing. That surprised me. Dog walking is not a business in Bangladesh. Here [in the U.S.] it's a business. In Bangladesh, you laugh [at the thought] that you can make money by dog walking.

Your bank has accomplished a lot, with 8.4 million loan customers. Yet you and the bank have come in for criticism: The bank doesn't follow government rules and regulations; the bank receives foreign funding.

Do I have this envelope with me so I don't have to answer all these questions? [Yunus hands me a 31-page pamphlet titled "Questions by critics on Grameen Bank and the facts." The answers in the pamphlet can be found on his website.]

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