Lisa Peck. (Fit People).

Plenty of weight-conscious American women anxiously stare at their thighs, usually before a full-length mirror at home or in a fitting room draped with a dozen different bathing suits. Ultrafit professional mountain biker Lisa Peck stares too--every week, when she needs to give herself a shot of Biogen's Avonex, a powerful multiple sclerosis (MS) drug treatment.

To steel herself for the shot, Lisa sits down, says aloud, "Consider the alternative," and slowly draws the needle plunger back to pull up the liquid that could lengthen her life and maintain its current high quality.

Now age 36, the Salt Lake City-based employment law attorney has alternately injected the top of her left leg and right leg every week since her 1996 MS diagnosis. But time hasn't dried her sweaty palms or calmed her butterfly-filled tummy.

When she hears the crinkle of the medication's wrapping, smells the rubbing alcohol, and pictures the 30-second shot, her anxiety balloons. Then, after she swabs the tiny puncture, flu-like symptoms dog her for the next 24 hours. She plans no racing and no court appearances the day after.

Yet, for all the private angst, Lisa couldn't be more public about discussing this neurological disease. With her well-conditioned body and silky blond hair she is the MS golden girl--a petite, articulate woman who shatters the hulking stereotype of the physically crippled, mentally diminished MS patient.

"I want people to know that MS has many faces," she explains. "Some of us ride in a wheelchair; others ride a mountain bike."

To raise MS awareness and bolster hope, she speaks nationally on behalf of pharmaceutical powerhouse Biogen and cycles on a team that recently incorporated that objective into its mission. She even litigates for MS patients protesting workplace discrimination.

Lisa projects a gritty passion, probably because, like many other MS sufferers, she spent years sheepishly feeling like a hypochondriac. After all, despite recurring blackouts, headaches, blurry vision, tingling sensations, and extreme vertigo--something she calls her personal Tilt-A-Whirl--doctors kept scratching their heads.

When Lisa finally got accurately diagnosed, the gnarled specter of her aunt appeared. By age 40 this woman lived in a convalescent home, where she quickly degenerated from delicately holding a teacup with two fingers to grasping it with both hands, to using the crook of her elbow, to being served by nurses' assistants. She soon died there--decades prematurely.

Still, Lisa found strange relief in knowing the name of her nemesis at last and becoming aware of today's much-improved treatments. Besides drug therapy she uses competitive mountain biking to optimize her health and wellness.

"I don't suffer much fatigue or depression, and I think it's because I constantly have endorphins running around in my system," she says, smiling with raised eyebrows.

Certainly, fighting illness with healthy eating and exercise habits helps. But it only quiets the tiger within. Flare-ups still happen. They produce a range of bizarre and unwelcome symptoms.

For instance, half of Lisa's face will inexplicably "freeze," or she will feel as if she's fresh from the dentist's office with a mouth full of Novocain that causes her to drool or go speechless. Those side effects, combined with blackouts, make her brutally aware of her dicey chemistry.

"The unnerving thing is that I don't know how long the symptoms will last or if I'll ever get back to normal," she confides with a hard-won resignation.

Perhaps that's where faith intersects with fitness. It is the immeasurable strength that keeps her engines burning even during the most spluttering moments. And in this regard, inspirational "Exhibit A" Lisa differs little from many others--she's an average Jane, walking through life on clay feet and trusting Someone bigger than she to pick up the slack.

She shares that she can't hit the pillow each night without first praying. Other times, she stops furiously peddling up a trail when she senses, with "my heart in my mouth," the great quiet vastness behind her so extravagantly displayed in Utah's panorama.

"My faith says that there's a reason for everything, even if I don't know why ... that there's a stronger force."

Pam Mellskog writes on health topics from Lafayette, Colorado.