No. 2 Go Light
Keep your pack as light as possible. I’ve hiked all over the U.S. and the world carrying heavy packs and light ones, and I’m convinced that carrying a heavy pack takes a harder toll on me physically than carrying a light pack twice as far.
No. 3 Don’t Kill Yourself
Hike at a pace—especially uphill—where you’re not pushing your heart or respiratory rates into the red zone, and take frequent, short breaks. Hiking is an endurance sport, not a sprint: Dial in a pace that you can maintain for hours rather than a pace at your upper limits, which will fatigue you much faster. On hard ascents, stop for a 30-second breather when you need to; even brief rests can provide a surprising degree of physical recovery.
Similarly, keep most of your longer breaks to sit for eating/treating water/bathroom/cooling feet to 15 to 20 minutes or less. That allows plenty of rest time without letting your muscles cool down completely, so you’re still ready to hit the trail at a strong pace.
No. 4 Get Out Early
Hike as much as possible of each day’s mileage in the cool hours of morning (or evening), because summer afternoons are typically hotter in many mid-latitude mountain ranges and desert canyons, and heat amplifies your fatigue. (On a related note, I always wear a sun hat, and a wide-brim hat protects you better than a ball cap.)
Not everyone likes to wake up early, and your trip doesn’t have to feel like work; just find a balance between how much sleep you need and minimizing your exposure to afternoon heat. Get organized in camp with gear to facilitate a quicker morning departure—eating breakfast and packing up doesn’t have to take two hours.