“Through training, I’ve learned to forgive my body for not being tall, blond and beautiful, and to revel instead in its strength and stamina.”

So here I am, on this blue-sky fall day, pushing my body down South Street with few of the other 5,000 runners in the Philadelphia Marathon in sight. Some cops directing traffic give me the thumbs up; others look at me like I’m a pain in their ass for keeping them away from their Sunday barbecues. But I smile at each one. No bad karma is going to intrude on my hard-won self-esteem.

I always wanted to run a marathon. In 1990, my last year of college, I was a fitness trainer majoring in phys ed. My final paper was on training athletes for events, with myself as my subject, going through six months of extensive workouts that included long runs, sprints and weights. I had a Reebok body that turned heads.

During this period, I nonchalantly walked into the department of health and took an HIV test. My new guy and I had decided that once we both tested negative, we could finally have the wild and crazy sex that we’d been murmuring about during our fluid-free make-out sessions. When my test came back positive, the relationship ended (later that same day), and I went into another world. I became afraid of my body. Afraid of the sexual attention it attracted. Afraid that it might deteriorate right before my eyes. So I guarded my body carefully, padding it with donuts, candy and cake -- food that hadn’t touched my lips in a decade. No one looked at me anymore.

After I graduated, I moved back to my hometown in Pennsylvania and never did anything more physically stressful than taking a walk. I wore one-size-fits-all shapeless clothes; I made decisions in a sugar haze; I was (I see now) in shock. For years I struggled with my weight, finally “redefining” my fat as “goddess flesh” in my search for peace with my body. Then, in 1997, I had a little brush with death: My platelets were revolting because of an HIV-related bone-marrow disease, and I was bleeding like crazy. I ended up having a hysterectomy. After surgery, I could barely walk.

The six months it took me to recover were more than a physical bottom; I was filled with fear. What I needed was to find a way to reaffirm my capacity to live a full life. When I heard that cyclist Lance Armstrong had won the Tour de France while battling testicular cancer, I decided that training for the 26.2-mile Philadelphia Marathon was just the affirmation I needed. I wanted to push and push and push -- and stop allowing HIV to dictate what I could do.

For 10 months, I ran six days a week, rain or shine, usually clocking two to four miles along the Delaware River. On Sundays I’d wake up at 5:00 a.m. and do my long runs, starting off at 10 miles and building up to 22. In winter, the path hardened, giving me shin splints. In summer, I carried bottles of water in my jog bra and in both hands. My day off was reserved for the weekly transfusion that helps me cope with my platelet problem -- the only AIDS medication I take. The side effects -- fatigue, nausea, anemia and ice-cold extremities -- can be brutal, but fortunately they last only a day.

Now, at mile six, I am wondering what happened to all that training. There are 20.2 miles to go, and my legs feel like lead. I find myself keeping pace with an old guy running alone in a t-shirt that reads “The Abominable Slow Man.” Everyone cheers him on. While we run together, he tells me about his back surgeries and how hard it is to keep his 78-year-old body moving. I tell him about my medical challenges, carefully editing out AIDS. We agree that running makes us feel alive. Suddenly I realize I’ve slowed my pace and am feeling better. I move on ahead with renewed faith. I started this running thing to feel strong about my body. I lost a little weight but a ton of negative thinking. Through training, I’ve learned to forgive my body for not being tall, blond and beautiful, and to revel instead in its strength and stamina. Now, whenever I feel tempted by some popular diet, I remind myself: It could all end tomorrow -- do I really want my last meal on Earth to be a Slimfast shake?

As I run through the open fields of Fairmont Park, I think of my friend Dawn Averritt, who is trekking the entire length of the Appalachian Trail on a five-drug combination therapy. For a moment, I feel her by my side, telling me I can do this. Suddenly I’m hit with memories of all the people I’ve lost in the past decade, and I stifle a sob. Some died bitter and angry, others just resigned. It’s always messy, and with little grace. And they’re all a part of me now.

My feet begin to blister at mile 11. As I reach a point where the race doubles back on itself, I pass near the finish line. Some marathoners are already there, but I’ll be running for at least two and a half more hours. How easy it would be to fade into the crowd, take off my race numbers and disappear. But I need to finish this race as much as I need to breathe. The pain worsens, each body part taking its turn to curse me -- first feet, then right knee, next left shoulder, finally back. But I’m on autopilot. At mile 20, I turn and head back the way I came for the final 6.2. By mile 24 every part of my body is shrilly complaining, and I am near collapse -- but my mind is focused only on the road.

At mile 25 a prerecorded message announces, “You are almost done with the Philadelphia Marathon. Smile and show your numbers.” I manage a grimace for the camera. Then I start to pick up speed. In the last half-mile strangers cheer and yell, “You’re almost there.” It becomes my mantra: You’re almost there, almost there, almost there. I repeat it through clenched teeth as tears flow down my cheeks. I can see the finish line. As I cross it, a man comes over and asks if I am all right. I break down: I made it.

The night before, I almost talked myself out of racing. I had a million excuses. But I ignored them, and I’m glad. I don’t know if my next marathon will be a 26.2 race through Philadelphia or a trek through the Himalayas. I do know that I will never use my illness as an excuse for anything again.