Heather Lambert is quick to smile.
She smiles when she plays with her two children. She smiles when she talks with her sparring partners at Kaze Dojo in Lisbon. She smiles when she comes face-to-face with opponents at weigh-ins before mixed martial arts matches.
"I'm smiling right up until I get in the cage," said Lambert.
But when the 33-year-old registered nurse steps into the cage where MMA fights are held, she turns serious, and that's bad news for opponents.
Two years after picking up mixed martial arts, a full-contact combat sport involving grappling and striking, Lambert has a 4-0 record and is the South Carolina Female State Champion at 120 pounds.
She will try to win her fifth match Friday when she faces Maria Rios at Global Fight League 13 at the Portland (Maine) Expo Center.
Her trainer, Kaze Dojo owner Greg Williams, said no matter the outcome Friday her fighting career has already been a success, because of its positive effect on her health and well-being.
"What she's accomplished already goes beyond all the medals and accolades you can get in sports," said Williams, "She's changed her life and she's doing something she loves."
Lambert originally signed up for cardio kickboxing to learn self defense three years ago. But her instructor noticed she possessed a strong kick and recommended she try other martial arts-based sports.
She trained for a year and made her competitive debut in a grappling tournament in Portland, Maine. Soon afterwards she was scheduled to participate in a kickboxing exhibition, as part of a challenge match between members of Kaze Dojo and the Vermont-based Green Mountain Boys.
Three days before the challenge match, there was a change of plans.
"Until three days before it was kickboxing, then it was swapped for MMA," said Lambert. "I really enjoyed it."
In the two years since then, Lambert has developed a passion for the sport. She trains roughly four days a week, alternating between grappling, boxing, kick boxing, MMA sparring and weight lifting. She normally spars with men, due to a lack of female sparring partners.
Sparring partners are selected jointly by Lambert and Williams.
"If women could train with other women, they'd jump at the chance," said Williams. "We don't really have another female in here, so the guys have made her what she is."
Training sessions can leave a mark. The first time Lambert was punched by a man, her immediate reaction was to kick him as hard as she could. She once gave a male sparring partner a black eye. In turn she has suffered a split lip, bloody nose and a concussion.
Said Lambert, "I got into [mixed martial arts] because I wanted to learn self defense. The only way to really test that is to really fight. You don't know how you're going to react to actually being hit until you are."
Her training regimen has proven effective. In her first MMA fight, she defeated Shannon Harney with a submission guillotine choke at Combat Zone 35 in Salem, N.H., on Oct. 26, 2010.
"When she got in the cage for her first fight it surprised me. I didn't think she would be as comfortable as she was, she did everything she had to do, at that point I was like 'wow'," said Williams. "That's when I realized she could be a fighter."
She notched three more victories this year.
In April she won by technical knockout over Melissa Demers at Combat Zone 37. She followed that with submission wins over Andy Nguyen at the South Carolina State Championship in May and Sarah McLeod at Victory Fighting Championships 35 in July.
On her left foot is a tattoo of the words "Sweet Dreams" surrounded by four stars, one for each win.
Her plan is to compete until she is 35 years old. But she admitted that plan could change. She is motivated to keep fighting out of her love of MMA and her competitive spirit.
Williams said she also has something to prove.
"Her goal in this sport is to really show that women can perform, it's not a freak show, it's not a side show, that women can be technically as good as men," said Williams. "It's an equality issue."
Friends and co-workers at the Grafton County Nursing Home have reacted with surprise to Lambert's fighting career.
Meanwhile her children Sydney, 12 and Joey, 9, are proud of their mother's accomplishments. Her success has inspired them.
"I think it's really cool, because she gets to express herself, and she shows that girls can be strong too," said Sydney.
Added Joey, "I was scared she was going to get hurt and everything, but now I'm not so scared because she's proven she's a really great fighter."
Lambert is confident heading into Friday's fight. She has followed a strict workout regimen, strengthened her body and honed her skills in preparation for her matchup with Rios. She brings the same work ethic to the classroom. A couple of years ago when she earned a nursing degree and graduated at the top of her class from Granite State Community College.
Lambert said training at Kaze Dojo has prepared her to face anything when she steps into the cage.
"I don't expect it to be harder than what I take here," said Lambert. "I feel prepared, and what's the worst that's going to happen? If I lose I lose. I don't have the fear of losing."
Williams said there was no telling what path Lambert's fighting career would take.
When she began taking MMA seriously, he took her aside and asked what her goals were. Remain a local fighter? Become a professional? Compete in a televised bout?
She replied that her only goal was to get better.
"She wants to see how far she can go. She doesn't want to set a limit," said Williams. "I think we'll both know how far is 'far enough.' I want what's good for her but I can give input. Only she'll know when she wants to stop."