On a 5-plus-day trek, the difference between a pleasant escape and a torture-fest boils down to physical preparation. Endurance is the ticket, but you need endurance that goes beyond daylong stamina. You need "toughness"--that gritty resilience that'll have you bounding out of the tent come morning to do it all over again. Use these guidelines to get there. Allow 6 to 10 weeks to train.
Gradually improve your staying power by increasing the length of your cardiovascular workouts. Start with 30 to 50 minutes; build to 75. Shoot for three or four sessions a week at a high intensity (a 7 on a scale of 1 to 10).
Once a week, put yourself through a marathon session. Like the distance runner who depends on long runs for endurance, prepare for a multiday trip with a moderately intense (5 to 6) power hike of 4 to 5 hours. (New hikers, start with 90 minutes, build to multiple hours by adding 15 to 30 minutes each week.) Hike at an aggressive pace with poles and a light (10-pound) pack, preferably on hilly terrain. Take breaks and don't forget fuel--a sandwich, or sports drinks and energy bars.
After 3 to 4 weeks of conditioning, string together the above workouts with no rest day in between to mimic the demands of a weeklong outing. Start with 3 days in a row (including the weekend workout); build to 6. Follow these guidelines to avoid injury.
» Increase the length of your workouts gradually (use guidelines above)
» Rest 1 day every week
» Mix up your workouts. Variety not only helps you avoid a repetitive stress injury, it also strengthens stabilizing muscles (those little ones we seldom think of until they're screaming on day 3). Power hike, run trails, climb hills, take a spin class, or do a circuit workout using a treadmill and elliptical trainer, varying the level and incline on both machines.