In an era when success in sports is supposedly all about hyperfocus and specialization, Sellers’s approach to long distance running is a throwback, an experiment in whether there might be a better way. Her decision to keep working at Banner-University Medical Center Tucson is not about the money or fearing that she will lose her career in medicine if she runs full time. She says doing it this way is going to help her run faster, especially now that her struggles with disordered eating are behind her.

“If I quit my job and trained full time, I don’t see it going well,” she said in an interview last month in New York, before she ran the New York City Half-Marathon. “I’d be a stress case and I’d be more injury prone. When I balance the two, I think I have better perspective.”

To those who know Sellers best, her borderline-bananas juggling act is about what they have come to expect.

Paul Pilkington, her coach now and when she ran at Weber State University in Ogden, Utah, said Sellers’s drive to push herself to the edge had been driving him nuts for years. Pilkington used to pair her with a slower Weber State teammate on recovery days and order Sellers not to push ahead. She would anyway.

In February, in the middle of her preparation for Boston, she traveled to Ogden for vacation. The training schedule called for her to push to 120 miles that week. She did that, and also went on daily hikes, including scaling two peaks above 8,000 feet. One day, she went skiing.