Two days later, her medal serves as a reminder of what could have been.
"It's great to have in your hand. The 'what ifs' start to plague you. What if I had decided to walk a little bit more?" she said.
O'Lin said her body was hurting, and she wanted to slow down. If she had, that would've put her right near the finish line at the time of the blasts.
"It could've been me running down there," she said. "It could've been my loved ones at the finished line."
She said the first explosion was surprising, but not scary. At first.
"I don't think anyone expects the worst at that moment," she said. "So people didn't look overly scared."
But then emotions started to change.
"People were starting to run in different directions towards the finished line with wheelchairs, so there was something going on. You couldn't count the number of ambulances there were," she recalled.
The Bakersfield resident was one of 12 local runners in Boston for the marathon. She touched base with one of the other Bakersfield people, who confirmed everyone was safe.
"At that point I was at ease to know that at least Bakersfield and our runners were safe," she said.
She won't let this stop her from running. She plans to participate in the Canadian Iron Man in August.
"Nobody would want you to stop running because of something like this," O'Lin said. "They'd want you to keep going and keep doing what you love."