When Mark Spencer was a child, he always arrived at the back of the pack.

"I was not a good runner to start out with because I had asthma as a kid," Spencer said. "In P.E. class, they'd time you running a mile and half and I sucked. I was the last one in class."

As Spencer grew, he started running a little more and found it helped clear up his asthma until it eventually disappeared. When he was a senior in high school, he took a backpacking and survival P.E. class that required he run on his own and record all the miles he had completed for a grade.

Since he was 18 years old, that exercise of writing down his miles has never stopped.

Spencer, now 50 and a resident of Fish Camp, is a handful of miles away from running enough miles to have circled the equator of the earth once -- 24,901.55 miles.

"I didn't really start out to do this," Spencer said. "It was just part of a P.E. class, but somewhere around five to six years ago I realized I was getting close to 200,000 miles and wondered what would be a cool end to it. I looked up the distance around the world and found out that would be a neat kind of milestone. It was something that just sort of happened."

Spencer's wife, Shirley Spencer, was not about to let her husband pass the milestone by without a party.

To honor his accomplishment, she's orchestrated his final five-mile jog in Wawona Sunday, inviting friends and anyone interested in running with him to come out and celebrate.

They're meeting up at 10 a.m. Sunday, April 3 at the Wawona Pioneer History Center parking lot. The five-mile run will go out to Wawona's swinging bridge, across the south fork of the Merced River, and end at Wawona's covered bridge.

"I'm really incredibly proud of him and I think it's very inspiring," Shirley said. "I think there is also a lot of bad news out there in the world and I thought, if there is something positive out there, why not share it."

For Mark and Shirley, Wawona is the perfect place to celebrate a milestone. The couple have a long history in Wawona -- working summers there together in college, running a climbing school at Camp Wawona from 79' to 88', and writing a Southern Yosemite Rock Climbs guide book highlighting routes in the area. Some of their favorite running trails are in Wawona, and Wawona is where Mark proposed to Shirley.

"People connect with different things, and I've always connected with this area and the Sierra Nevada," Mark said. "I've traveled around the world, but it's always like coming home when I get back here. Running on a trail in Yosemite is my favorite part."

Mark, who's been on five of the seven continents, mostly mountaineering, has a résumé of adventures that could fill hundreds of stories: working on the high altitude rescue team on Denali in Alaska, climbing 45 peaks over 14,000 feet in elevation -- 20 of them higher than Mount Whitney, holding the fastest record for more than 20 years of running up and down Half Dome starting at Happy Isles in Yosemite (138.45 minutes up and 113.11 minutes down), and working on American Ambulance's original rescue team and as a paramedic for the company for 20 years.

He now works as a firefighter in Sanger, and teaches high altitude rescue classes at Regional Medical Center in Fresno for medical students, with more adventures planned for the future. He'll climb Mount Kilimanjaro next winter, and has a goal of running up Half Dome 100 times. He and Shirley are also planning to climb the highest mountain in every state, with 45 of 50 already complete.

Mark is signed up for at least five massive races this year, including the American River 50 Mile Endurance Run in April. Throughout his life, he's run 140 races, about 30 marathons, and some ultras, races that are longer than a marathon. Mark typically runs six to seven races a year.

While Mark enjoys competing, winning isn't important -- although does have his share of medals, including "Runner of the Year" in 1988 for Oakhurst's Runner of the Year series, a number of races in the area.

"It's the journey along the way that counts, and the finish line is a secondary thing. It's just a bonus," Mark said. "I think for me, in running or racing, you've really got to be doing it for yourself. It's got to be worthwhile for you, because if you're doing it for other reasons, there are a lot easier things to do. There's always going to be faster people than you. Like big mountains, you really have to love big mountains to be on them."

A classic statement for Mark is, "Come on, it'll be fun," said Shirley, a phrase so commonly heard among his friends they printed it on the back of some t-shirts in his honor.

For Mark, it's the fun, the love of the experience, that is the true source of his inspiration. And there's really no place like home.

"This is where the action is for us, in the big trees," said Mark of living in Fish Camp. "We're back where we belong. I can't imagine anything much better than going down a trail in Yosemite."