BOSTON - Chris Larcome had no problem searching for inspiration through the pain, the wind, rain, mud, cramping and every other roadblock thrown his way for 26.2 miles from Hopkinton to Boston yesterday.

Here are two reasons why:

Four years ago his wife, Mary, weeks after giving birth to their second child, was diagnosed with Multiple Sclerosis.

Fifteen months ago, at 5-10 and 258 pounds, Larcome diagnosed himself as a beached whale.

"There were so many things that could have gone wrong (yesterday), especially at the start with all of the mud, rain and cold," said Larcome, who ran his first marathon yesterday. "But let's be honest; Nothing was going to stop me, not with so many people, especially my wife, counting on me."

Larcome, of Atkinson, N.H. via Methuen, gets emotional sometimes when he talks about it, just like he did when doctors gave he his wife the reason her hands were trembling.

She had MS.

"That was a tough day," recalled Larcome. "I was the one who was crying."

Larcome, an accountant for Comcast in Reading, had problems dealing with an unknown future. One of his strengths is planning, a trait, he figures, that probably pushed him into accounting. With his wife being diagnosed with debilitating and incurable disease at age 35, he didn't know how to deal with it.

One way, he thinks, was eating.

"I remember going to give blood when the nurse took my blood pressure and said it was too much of a risk," said Larcome, a 1989 Central Catholic graduate and 1994 Merrimack College grad.

"It really shook me up," he said. "I started thinking about how bad I was physically; how my wife needed me; how my kids needed their father to be around."

On Jan. 4, 2006 - "I'll never forget the date," he said - Larcome went to the gym and stopped eating "like a pig."

By July he had lost about 100 pounds. Through yesterday's race, he weighed 160 pounds ... the 100 pounds gone but not forgotten.

"It really taught me about inner strength," said Larcome. "It showed I can do something when I apply myself."

Enter talk about the Boston Marathon. Larcome talked to his wife, who for three years has taken a Copaxone shot, which treats MS, every day.

Larcome applied for a number at the Boston Marathon through the MS Foundation. It entailed writing a letter to show he was worthy.

Larcome got the number, which was sort of like be careful what you wish for.

He began going to the gym at 4:30 a.m., getting home around 7 a.m., just when the boys, Jack and Sam, were waking up. He didn't want to miss one minute away from his family.

"The toughest part was training and I could not have done it without the support of Amy Bernard," said Larcome, of family friend and Pinkerton Academy track coach. "She got me through so many tough times. I can't thank her enough for her support."

Yesterday's race did not go as planned. Larcome says he was in shape to run a 3:30. That wasn't about to happen with the wind, rain and fear running through his veins.

But he labored through several cramps, having to walk a few times, and strolled by the Boston Public Library 4:24:38, barely.

Afterward, it was his wife who was fighting back the tears.

"He is so strong," said Mary Larcome, who said a symptom of MS is slightly slurred speech. "To lose the weight the way he did and now to do this for me and MS, I really don't know what to say ... I am so proud of him."

In the end, Larcome raised about $5,500 for MS.

"My wife is doing great. My kids are great, too," said Larcome. "I can't tell you what this means to me. The weight is never coming back. And I want to run the marathon again next year. Trust me, I will run a better time."