I had a very important hiking experience this past weekend, where I learned that physical conditioning isn't the only important thing. Trail conditions, nutrition, etc. are all equally if not more important. At one point I found myself alone, traversing an ice field laterally across a slope where if something were to go wrong, if would go very wrong, very fast. Literally had knock knees for about 20 seconds before getting myself under control again as we passed through an area where somebody had died a few weeks earlier. To boot, I had never used an ice ax before and spent too much time thinking about how much I didn't want to have to self-arrest...The body was picked up the day after we completed the hike.

It was mentally and emotionally taxing, but a great preparation for future hikes of that magnitude of difficulty and up.

Edit: Oh also I lost 3 lbs that day despite packing what I thought was a lot of food, and bringing a water filter to attempt to stay hydrated. It was 90 degrees out the entire day, and as you can see there was no shade.