Welcome to strangers from KCW and Radiotopia.

I'm Leah Tao.

And over the past three episodes, we've been following the story of Elizabeth, who decided to give a kidney to a stranger,

and Mary, who became the recipient of Elizabeth's kidney.

When we left them last, they were just out of surgery, and all had gone well.

But there was some pain, of course, especially for Elizabeth, who had voluntarily had an organ cut out of her body.

And the recovery proved harder than she'd expected.

When I spoke with her in December, about six weeks after the surgery,

and shortly before Christmas, when she had just gone back to work,

it was clear that it had been frustrating.

Just being sick of being in pain and sick of being stuck in the house

and sick of not sleeping right,

and there's definitely an element of being on pain

medication that makes you not quite yourself and just not bouncing back as fast as I thought I was

going to. I had expectations of being back to work in four weeks and it ended up being six, being out

of the hospital in three days and it ended up being six, being out of the hospital in three days, and it ended up being five.

And knowing that I had this huge project that was sitting on my desk at work

and that the holiday break was coming up,

I was only going to have those four days of work and then back to being off work again.

So it was just anxiety about that.

But then came the new year, and Elizabeth was feeling better.

She started running again, not at her pre-surgery speed right away,

...