"To stave off injuries and enjoy your outing more, you should boost your endurance for strenuous hikes farther than five miles," advises James Fisher, a personal trainer in Sedona, Arizona. No nearby trails to practice on? Follow his four-week treadmill plan to get in hill-bounding shape.

>>Three to 4 times a week, walk at a brisk pace-aim for 4 mph or faster-alternating between a 2 and 4 percent incline every 5 minutes for half an hour.

>>At the start of each consecutive week, increase your maximum incline 2 levels, make your minimum incline half that amount (so 3 and 6 percent, 4 and 8 percent, etc.), and ramp up your workout time by 10 minutes.

>>By the end of the month you'll be switching from a 5 to 10 percent grade every 5 minutes for an hour while still keeping a quick clip.

>>Another option: Some hikers we know do some training with a weighted walking vest (check it out here).