Here's a quote from a thru hiker gear review. He had hiked the John Muir Trail -

"Of course this information all begs the question, what is the one thing I wish I had brought that I didn't? Ibuprofen. Yes. I brought some pain killers but I was mostly thinking about high altitude headaches when I packed it and only brought a few. To keep up the pace of 16 miles per day, I had to beg the other guys for their pain killers."

My trip this summer: backup matches or lighter.

Last year, I brought the Diamox, but didn't need it.

So, of course, this year I didn't bring it and needed it. I won't make that mistake again.

TP and lots of it.

A refrigerator with a really long extension cord.

Less pounds.

Dictionary to explain the term "to beg the question".

Aside from that: time. A lot more time.

Jagermeister and a couple of cans of Shark.

My Dad

Most dictionaries are probably already legitimizing the misuse in their descriptivist zeal...

On my first-timer main trail ascent this July, I wished I'd brought a dumpster so I could toss my extra food, and a shaman to clear up the monsoon so I could see.

On my MR dayhike the next month, I wished I'd brought along a partner who knew which route to follow below Iceberg, and which #@$! chute to climb above it!