I see hikers who have a rough start on the trail and I ask them a question.
Did they try doing day hikes before the hike. If you can't day hike your typical
days mileage around town when you don't have a full pack, you shouldn't
expect that the trail days with pack and ups/downs will be easy.

I try to do 9-10 mile neighborhood walks a few months before the trail.
I also do a few 12-15 mile day hikes in the mountain in the few weeks before
a major hike. Our typical couple hour walk around town can be 7-9 miles.

The second reason people have problems is they bring too much stuff.

Jeff
_________________________
Jeff MyBackpackTrips