My favorite travel memory would probably be when I took an ATV tour of the countryside surrounding Phonm Penh, Cambodia. It was my birthday, and it was hands down one of the coolest things I've ever done.
The people living in the countryside live to completely different standards than what most Americans might be used to, and they don't exactly have a lot of material possessions. However, I learned that happiness does not always come from what sort of iPhone you have, or how much money is in your bank account, but really it's about the experiences and people you surround yourself. I got some time to interact with the countryside people, and they all seemed so polite, friendly, fun-loving, and were happy with simple things.
Not to mention, on the way back, it started storming and I ended up traversing through mud and flowing water all with lightning in the background. I came back to my hotel caked with mud really feeling like I just took part in a Die Hard movie or something. One for the memories for sure.