After an absence of 18 years, Joan Benoit Samuelson will run the Boston Marathon once more.

Ever the frugal Mainer, Samuelson said she didn’t want to waste all those 20-mile runs she put in over the winter, not to mention extensive Alpine and Nordic skiing culminating in an exhaustive six-day trek through the Alps from Chamonix, France to Zermatt, Switzerland with her husband Scott at the end of March.

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JOAN BENOIT SAMUELSON AP file photo

She called The Haute Route, as it is known by mountaineers, “probably the most physically active, demanding endeavor I’ve ever undertaken.”

Speaking on a conference call Monday afternoon with half a dozen reporters, Samuelson said she had been thinking about running Boston since the beginning of the year but held off until completing the treacherous hut-to-hut trip through such peaks as Mont Blanc and the Matterhorn.

“I didn’t want to commit until I finished that trip,” she said. “I didn’t know if the trip would make me or break me. I will confess that it did a little bit of each.”

The 115th running of the 26.2-mile race from Hopkinton to Boston is scheduled for Monday. Instead of starting with the elite women at 9:32 a.m., Samuelson said she prefers to run among the masses that, for the first time at Boston, will include her 23-year-old daughter, Abby.

They also ran together in October in Chicago, where Abby qualified for Boston and Joan missed qualifying for the 2012 Olympic Trials by less than two minutes, in part because of temperatures that climbed to 80 degrees.

She finished in 2 hours, 47 minutes and 50 seconds. In Boston, she would need to break 2:46 to qualify for an unprecedented fifth Olympic Trials.

Her last Trials performance came in 2008 in Boston, although on a loop course, not on the traditional marathon route. The outpouring of emotion from a Boston crowd that has adored her since she toddled down Boylston Street in ’79 as a fresh-faced New England college kid wearing a Red Sox painters cap played a role in her decision to return.

“I have never run a race where I had so much support as I did at the Olympic Trials (in 2008),” she said. “The crowds really kept me going.”

Even so, she down-played any thoughts of a Trials-qualifying performance.

“I’m not really thinking about Olympic Trials or times,” she said. “I can’t do that to myself at this stage in the game.”

Samuelson last ran the Boston Marathon in 1993, when she placed sixth in 2:35:43. Her 1979 victory as a 21-year-old set an American record of 2:35:15 and her 1983 victory set a world record of 2:22:43 and remains the fourth-fastest time in Boston Marathon history.

“I’m really looking forward to getting back on the course,” she said. “It’s home. I feel grounded there.”

During a run Monday morning in Freeport, she was nearly grounded by the elements.

“I almost fell on an icy spot,” she said, “and two minutes later I was almost struck down by lightning. So it’s been a long winter. But I would say I’m feeling very strong as a result of the winter.”