You're going to be sore tomorrow," says Pete Fernandez, the professional boxing trainer and former pro fighter who teaches Boxing for Fitness at Xtreme Health & Fitness Center.

I've just been introduced to the four rudimentary punches of the sport: the jab, the straight, the hook and the uppercut. The class hasn't even started yet and Fernandez, who's seen countless novices try their hands at a boxer's workout, has already sized me up and made his prediction.

He's right.

I wake up the next morning with my calves, arms and abs — worst of all my abs — radiating that oddly satisfying heat that comes when your muscles repair themselves.

Feeling as if I've been thrown from a horse, I recall how poorly I did in the class. Broken into three-minute rounds with one-minute breaks, classes run approximately 45 minutes, and I was winded during the first exercise, a sideways gallop around the gym's boxing ring. During two rounds of shadow boxing, I struggled to keep pace. Attempting to jump rope for a round, I felt as if my feet belonged to someone else. Then came hitting a heavy bag for two rounds, which forced me to double over several times to catch my breath. The last three rounds — hopping onto and off of a step, and throwing combinations at hand-held punching mitts — were lost in a blur of exhaustion.

I had gone into the class hoping for a good workout and got more than I bargained for. Having jogged and lifted weights with little enthusiasm for more than a year, I saw the class as an opportunity to exercise with a practical application: learning basic self-defense. And although I knew I'd never be "a contenda," it was humbling to barely muster through, fatigued and ragged, while those around me, regulars of the class, maintained their poise and focus, exerting themselves with purposeful calm. But amid my panting, sweating and suffering, something unexpected happened. I had fun.

The physicality of boxing jarred me from my more mundane workouts. The sport's demand for total body coordination forced me to work muscle groups I'd always ignored. Striking heavy bags and focus mitts tapped my everyday stress, expending it as directly as throwing gasoline on a fire. Unlike with most sports, there was no waiting turns or calling for someone to pass the ball. And although I'll never come close to the skill displayed by top boxers, in that first class I threw a strong straight right that connected with a heavy bag about an inch from full extension, snapping the shot with a gratifying "Mmphh." It wasn't much, but it felt right.

Three days later, I'm back in the boxing gym at Xtreme, getting my hands wrapped and trying to glean some tips from Joe Sanchez, a pro boxer and one of the trainers who assist Fernandez. "You gotta stay calm," he tells me. "Pace yourself. Boxing is about endurance."

This is news to me. In the few fights I've seen on ESPN and HBO, I've been oblivious to how well conditioned the fighters were. Perplexed by the idea of staying calm during a fight, but with Joe's advice in mind, I set a goal to make it through an entire class without running out of gas.

Two months later I succeed. I shuffle around the ring with ease. I shadow box smoothly. I get used to the jump rope after finding my feet. I'm hitting the heavy bags with consistent force. I'm jumping on and off the step for a full round — no cakewalk. And I can throw simple combinations into the mitts without getting too sloppy. I'm beginning to feel pretty good about myself. Then the trainers, seeing my readiness to do a bit more, start working me harder.

The trainers, as if by some rule, are all the charming combination of formidable and personable. They're sweet enough to greet some of the young ladies who are regulars of the class with a kiss on the cheek, yet they're imposing enough that if they tell you to do something, you do it.

So it's with an amicable brand of authority that these guys increasingly critique my stance, demonstrate how to rotate my hips into hooks, demand that I put more into my punches and show me tougher combinations that include slipping jabs and ducking hooks.

After about five months of regularly attending the class, I'd love to say that I'm looking like the next Roy Jones Jr., but in fact I'd be afraid to even hold the mitts for him.

My gains, however, are significant. I go about my days with decreased tension and increased energy. If I were caught in an unavoidable fight, I'm confident I could protect myself against most guys my size. And the thing I'm most proud of: The top ridge of my abdominal muscles is clearly defined as two segments. It's no "six pack," but I like to jokingly call it my 2Pac.

If I had known I'd enjoy a boxer's workout this much, I'd have gotten into boxing a long time ago.

My advice for anyone interested in trying a boxing class: Drink at least a liter of water beforehand.

And keep those hands up.

Area gyms offering boxing instruction:

Hillsborough: Calta's Ring Sports Boxing, 14968 N. Florida Ave., Tampa (813-963-5565); Calta's Fitness Clubs, 4241 E. Busch Blvd. (813-963-5565) and 4320 W. Gandy Blvd., Tampa (813-963-5565); Calta's Ring Sports Boxing, 4913 W. Waters Ave., Tampa (813-963-5565); Xtreme Total Health & Fitness, 936 S. Howard Ave., Tampa (813-258-2639).

Pinellas: Fourth Street Boxing, 2710 Fourth St. N., St. Petersburg (727-892-6900); Dunedin Boxing Club, 1241 San Christopher Drive, Clearwater (727-736-2826).

This article appears in May 13-19, 2004.