Jenn Davis hiked the 2,175 miles that make up the Appalachian Trail the year she graduated high school. She and her two hiking companions thought it'd make a cool senior project.

Rising as soon as they heard birds chirping just before sunrise, they'd boil water for a hot drink and oatmeal, pack up and hit the trail. Once they got their trail legs, they'd average 25-30 miles a day. On a good day, they would make 50.

Twenty-five miles a day, nearly every day, for roughly five months is an extreme example of long-distance backpacking. Davis, now a designer and saleswoman at REI-Pittsburgh, tells her backpacking customers that if she can endure months on the trail, just about anyone can handle a long-haul trip of several days. The trick is to be prepared.

In concept, long-distance backpacking is a fairly simple thing. You pack your gear, pick a trail and start to walk. The hardest part is getting time off work.

But for beginners, the details and planning necessary to enjoy four-plus days of hiking can be daunting.

What should you eat? How much food should you bring? What clothes should you wear? Where should you go? What's essential, what's fluff? How do you pack? What about drinking water? Are sneakers OK to hike in?

Breeeeathe... Here's a beginner's guide to long-distance backpacking. Now you'll have no excuse not to hit the trail this summer.

So you've got the whole walking part down. What to take and where to go are the next obstacles.

On your back you'll carry a tent, sleeping bag, sleeping pad, backpack, stove, fuel, headlamp, Swiss Army knife, boots, iodine tablets and water filter, water bottle or two, enviro-friendly camp soap, pots, pans, lighter, bowl, cutlery, First-Aid kit, bug spray (DEET is the only proven product), toothbrush and paste, plastic trash bags, rain gear, sunscreen and all the food and clothing necessary for a trip of that duration. The key word of that sentence being "necessary." And don't forget a deck of cards.

That's a lot to take in, so start at the bottom -- your feet.

"We joke that there are two things that can cause pain on a backpacking trip -- your boots and your pack," said Nate Twichell, 31, of New Stanton, an employee at Exkursion Outfitters. "If those don't fit well, it's gonna be a painful, miserable experience. If your pants don't fit right, it's probably not going to ruin your day. If you're boots don't fit right, you're gonna know right away."

Exkursion, in Monroeville, is a small store stuffed with every possible outdoor necessity. Above racks of clothes hang colorful sea kayaks, strapped to the ceiling with climbing webbing. Behind the counter are ice screws, climbing helmets and ice axes. In the back, across from the rows of packs, is a small climbing wall to test climbing shoes on. A bouldering pad is spread below it, making for a soft (or softer) landing.

Twichell, sitting in front of a wall of leather boots, plastic mountaineering boots, trail runners and sandals, pulls a nearby shoe off its pedestal and begins to explain about torsional stiffness and where a shoe should flex. In short: footwear should be stiff on the long-axis and should bend only at the ball of your foot. Twichell demonstrates by bending a light day-hiking boot in half.

"Your foot doesn't bend there," he said. "If you've got a 40-pound pack on and you're on rocky terrain, your arch is really going to feel that."

As for toe boxes, Twichell says to keep them roomy. Heel fit (keep them tight), trying shoes on (take your time) and breaking in shoes (do it slowly).

"A lot of folks get over-excited and want to go out right away and spend a day hiking in them right out of the box. At that point, you're not breaking the boot in, the boot is breaking your foot in."

There are lots of things you can borrow from friends -- tent, sleeping bag, headlamp, stove. A backpack is not one of them.

Packs are not only fit specifically for an individual's hips, shoulders and back, they also fit that person's packing style. Finding a pack and fitting it properly to your back and hips can take some time. Hikers shopping for a pack should be willing to devote about an hour to finding one and having it fitted.

There's little difference between the rest of the gear -- clothing, stove, pots and pans, etc. -- that you'd carry on weekend trip and what you'd need for a week-long adventure.

Food, however, is another matter.

Long-distance packing requires balancing the need for high-energy food reserves with economy of weight. Some distance hikers are Ramen noodles and Pop-Tarts people. Others cook "gourmet" food, making pizza and other dinners that take more preparation than boiling a pot of water. It depends on how much weight a backpacker is willing to carry, and how much work he or she is willing to do before meals.

"Folks should experiment with food, play with it at home, see what will work ... but know everything tastes a lot better in the woods," said Twichell. "The freeze-dried chili mac with beef might seem disgusting at home, but when you're tired and hungry ... it's pretty good."

It's easy to overpack when it comes to food. Plan out each day's meals with foods high in calories and protein, like gorp and Snickers.

Ben Cramer, editor of "Pennsylvania Hiking Trails" (Stackpole Books), has hiked approximately 3,000 miles of Pennsylvania trails. On the trail, he says, he carries, "a lot of dry food, so it's not too heavy. The key is you need to have a lot of energy when you're backpacking. I personally take a lot of chocolate and cookies. A lot of the veterans would recommend granola and raisins and nuts."

Now, where should you take your new pack, broken-in boots and packages of chili mac?

In Southwest Pennsylvania, it's easy to find a trail you're comfortable with that is within easy driving distance. Reference books and Web sites are plentiful. Cramer's book lists and describes hundreds of trails around Pennsylvania. Tom Thwaites' "50 Hikes in Western Pennsylvania" and Rhondi and George Ostertag's "Hiking Pennsylvania" are good resources. Slackerpacker.com includes a fairly thorough Pennsylvania Hiking Trail Finder index.

Ultimately, Davis tells her long-haul customers, backpackers have nothing to prove to anyone.

"Take one step at a time," she said. "Just enjoy it, 'cause it's not a race. It's just fun."