Born in Cape Elizabeth, Maine, Benoit took to long-distance running to help recover from a broken leg suffered while slalom skiing.

Despite having surgery on her Achilles tendons two years earlier, she repeated her marathon success with a victory in 1983, setting a course record of 2:22:43.

[10] Benoit enjoyed success at non-marathon distances as well, winning the prestigious Falmouth Road Race (7.1 miles), a total of six times (1976, 1978, 1981–1983, and 1985), breaking the course record on four of those occasions.

In 2003, at age 46, Benoit won the Maine half-marathon, defeating a field dominated by runners two decades her junior, and she was faster than all but six men overall, finishing in 1:18.

At the 2008 US Olympic Team trials, at the age of 50, she finished in 2:49:08, setting a new US 50+ record and beating her personal goal at the time of a mid-2:50s marathon.

When she ran the New York City Marathon on November 1, 2009, she broke the Senior Masters record for runners older than 50 with a final time of 2:49:09.

Later that month, she ran in the Athens Classic Marathon for fun and finished in 3:02, the slowest time of her career; she was not fully healed from her Chicago performance.

[18] In addition to her running, as of 2014[update], she serves as a coach to women's cross-country and long-distance athletes, and is a motivational speaker and sports commentator.

Benoit and her husband, Scott Samuelson, whom she met when they were both students at Bowdoin College,[19] have two children, daughter Abby and son Anders, who are runners in their own right and shared the running of the 2014 Boston Marathon with their mother.

This allowed her to win her age group (60–64) by nearly nine minutes, but falling short of the overall (3:01:30) fastest time by a woman over 60 in a marathon.