NAHANT – Dawna Nocera loves to run. She loves the way she feels when she has that runner’s high.”It’s freeing,” says Nocera, 49, who will be running in her fourth Boston Marathon Monday. “When I’m running, I feel happy ? like a million bucks. I have a smile on my face, and I feel like I could go on forever.”Well, if she can’t go on forever, she’ll settle for 26.3 miles in 4:05 (only two seconds faster than the time she ran last year). If she does that, she’ll automatically qualify for next year’s race.But love of running is only half her story. The other half involves her grandfather, Albert Hill, who was a gold medalist in the 800- and 1500-meter runs in the 1920 Olympics in Antwerp, Belgium.”I think of him when I’m running,” she says. “I did know him (she was 10 when he died). As an elderly gentleman, he was in terrific shape and was very vital.”It’s a way to feel connected to him,” Nocera says. “I get those warm, fuzzy feelings, and whenever I think of him when I’m running, it’s always an emotional moment.”She ran her first Marathon 10 years ago with the Lynn YMCA, under the guidance of the fitness director at the time, Bart Meuse.”For him to put the idea in my mind, I will be forever grateful,” she says. “I think he saw that I was a runner. When I used to go there, I used to lift weights and I used to run around the track. He knew that.”He’d put signs up about running in the Marathon, and I thought that I could never do that,” she said. “He told me a couple of times how they went nice and slow in the beginning ? and course I could do it ? and he was right.”Nocera, who owns a ballroom dancing studio in Woburn (and is also an organizer for the Eastern US DanceSports Championships), usually runs around town on her short runs, but will go from the Tides all the way up through Marblehead on her longer training runs (which are over for now).She feels that people look at the Boston Marathon as a benchmark, the same way mountain climbers perhaps view Mt. Everest.”People like to do it because the course is supposed to be difficult,” she says. “People like the challenge of going against people who have a fast race.”The race is said to be faster because you have to qualify to run it,” she says.She adds that the race has a lot of history associated with it, which also makes it attractive.”It was the first one ever, in this country, I believe,” she says, “and it’s also the first one where a woman (Kathy Switzer) ran.”Come Monday night, Nocera will have a sense of relief about her.”We’ll go get something to eat at Faneuil Hall, and then crash,” she says.