You have a date on the calendar. Here is how to count backwards from it.
The useful thing about a hiking trip is that it has a date. You cannot negotiate with it, and you cannot decide in week six that you would rather peak in the autumn. That makes it one of the easier things to train for, as long as you count backwards from the date instead of forwards from today.
Before anything else, write down four numbers: days of walking, hours per day, elevation gain on the biggest day, and pack weight. Everything below scales off those four. A five-day hut-to-hut with a 15 lb daypack is a different job from three days with 35 lb on your back, and the second one is mostly about the pack.
What the trail asks of you, roughly in order of how often it is the thing that ruins the trip:
Twelve weeks is comfortable. Eight is enough for a moderate trip. The structure is the same either way, the blocks just get shorter.
Build the habit and the tissue tolerance before the difficulty. Each week: one longer hike or hilly walk of 2 to 3 hours with a light pack (10 to 15 lb), two strength sessions, and two or three easy aerobic sessions of 30 to 45 minutes. Do not add pack weight yet.
Now the long day grows and the pack gets heavier, but never in the same week. Alternate: one week add 30 to 45 minutes, next week add 3 to 5 lb. The long hike goes from 3 hours toward 5. Keep two strength sessions, start emphasizing the slow lowering described below, and add deliberate downhill.
This block should look like the trip. Pack near trip weight. Elevation gain on your long day at 60 to 80 percent of your biggest trip day. Wear the actual boots and socks and carry the actual pack. If the trip has back-to-back days, do at least two back-to-back weekends: a long Saturday followed by a moderate 2 hour Sunday on tired legs. That Sunday is the one that tells you the truth.
Cut the long day roughly in half. Keep the frequency, drop the duration and the pack weight. One short strength session early in the week at half the usual sets, then nothing heavy in the last 5 days. You cannot gain fitness in the last week, and you can absolutely arrive tired.
Two sessions a week, 35 to 45 minutes. Four or five exercises. The list is short because the specific ones matter.
Forward step-up onto a knee-height box, holding dumbbells or wearing your pack. This is the closest thing in a gym to climbing with a load. Start at 3 sets of 8 per leg with bodyweight and progress to loaded sets of 10 to 15. Step up without pushing off the trailing foot, and lower under control rather than dropping.
Rear-foot-elevated split squat or reverse lunge, 3 sets of 6 to 10 per leg. From week 5, use a 3-second lowering phase on at least one of these. That trains the eccentric quad strength descending demands, and it decides whether day two starts functional or wrecked.
Farmer carry (weight in both hands) and suitcase carry (weight in one hand, harder and more useful), 3 to 4 rounds of 30 to 45 seconds. This builds the trunk, grip, and upper back tolerance a pack asks for, and it is why your shoulders stop screaming by hour four.
Romanian deadlift or single-leg Romanian deadlift, 3 sets of 6 to 10. Glutes and hamstrings do a large share of the uphill work and are usually the weakest link.
Straight-leg and bent-knee calf raises, 2 to 3 sets of 12 to 20; calves take an enormous share of the load on steep ground and in stiff boots. Add side planks and a hip abduction movement (side-lying raises or banded side steps), 2 sets each, plus dead bugs or a Pallof press. Balancing on one leg with your eyes closed for 30 seconds a side costs nothing and pays off on uneven ground.
Start at 10 to 15 percent of your body weight, or half your trip weight, whichever is lighter. Add roughly 5 percent of the current load per week and cap it at your actual trip weight; there is no benefit to training heavier than you will carry. Never add weight and distance in the same week. Use water jugs so you can pour weight out if a session goes badly, and carry the real pack for the last four weeks so you find the hot spots at home.
Train descending deliberately from week 5. Find a hill, walk up and back down repeatedly with the pack on, at the pace you would actually take it. Expect two or three days of soreness the first couple of times, and expect it to almost vanish within three or four sessions. That is the adaptation you came for. Train with poles if you plan to use them.
New boots need at least 20 to 30 miles first, including long days with the pack. Blisters are a training variable, not bad luck: one in week 7 is something to fix while it is still cheap.
This happens constantly. It is workable, it just means choosing. Keep three things and let the rest go:
What to cut: the extra easy aerobic sessions beyond one, the upper body work, and the ambition. What not to do: double the pack weight in a fortnight to catch up. Hold the one-change-per-week rule, accept less base than you would like, and adjust the trip where you can. A shorter first day, or one extra rest day mid-trip, buys back more than any amount of panicked training.
If you are three weeks out, do not train harder. Walk a lot, sort the boots, practice descents gently, and go in fresh. Under-trained and rested beats under-trained and injured.
Let's Gooo is an iPhone app where you build your strength training by talking to a coach named Carlos. It fits this particular problem because a trip is exactly the kind of thing you have to tell a plan about, and most plans have nowhere to put that information.
Being straight about the limits: it does not plan your hikes, pick your route, or write a hiking-specific endurance schedule. It builds the strength side around the trip and keeps your walking and hiking in the same picture.
Free to download. iPhone. You always have the final say on your plan.