"My heart was racing and all I could think about was the possibilities for all the horrible things that could happen," she said. "I just kept deep-breathing through it, and then the doctor led us through, I don't even really remember exactly what he said, but just to remember how the disease [had] stolen so much from us, and I don't know what hit me and I just got a little emotional and a few tears ... It's very emotional for me."
There was one more challenge ahead. It was back at the hotel. The test: Campers had to put a hand on a public toilet seat, then put something in their mouths with the same hand.
"My whole life I spend doing this," said Grayson. "It is gross and somewhat risky but OK, I've only been doing it 30 years. Which is not to say it's safe...
"OCD is like cancer... it grows and it gets out of control. So you know what? When you treat cancer, you cut it out. So if you chose to do this, you are cutting out the cancer -- and if you don't have contamination, you are supporting other people. We're not saying it's safe, we're saying life is a risk so we are taking a risk."
But it was more than Lange could handle.
"He wanted us to touch the toilets and then eat a tic-tac without washing our hands, and I just knew from the dumpster experience that I just can't handle that right now," she said.
The conference was more than five months ago now. But just the other day, "Nightline" paid a visit on Lange at home. She said she really took something home from the conference.
"Every time I have a difficult time or difficult day with the OCD, I think back on that, and I think about how many things I haven't been present for, been either worried or anxious and just so much of my life was taken," Lange said.
The message, she said, was that the worries aren't worth it. Now, Lange has her morning routine down to about five minutes, from 20 last summer. And then we went out because she wanted to show us another breakthrough, at a local coffee shop.
There was a door handle.
"[Usually] I would use my coat or bring a bleach wipe," Lange said.
Now, no problem: She grabs the handle with her bare hand and walks right in.
And that is progress.