Travel to Your Limits
I traveled an unbelievable amount as a child. I'm sure I'll forget some, but I've spent considerable time (as in weeks, and often months) in Turkey, Iceland, England, France, Alaska/Yukon, Hawaii, Australia, New Zealand, China, Bahamas. I only think recently have I come to realize how influential those amazing trips were to my development as a person.
There's something almost spiritual about the experience of a long trip to a foreign land. I remember when in China we stopped at a small convenience store off the beaten track, full of local Chinese who had otherwise never seen an American. This one guy, about my age, approached me with this amazing sense of fascination in his eyes. I remember he shook my hand, and gave a small bow of sorts. Neither of us knew a single word of the other person's language, but in that moment we both shared a message without words of how much we wished we could share in the other's lives for a short while, just to see things from their wildly unknown perspective.
When I was in Paris I remember an artist approached us at the Museum for Modern Art. He spoke just a little English. He also shared that indescribable look of unique fascination, and managed to say "you are my brother".
The way my memory works, (and I suspect everyone's), is that certain very-short episodes are ingrained in vivid detail. Almost everything else is lost. When I think of any event in the past, it's a collection of quick shots, not a long summary or full exposition. The trips I've taken fill so much of my memory-bank.
I think your best memories are those resulting from events of unequivocality (in the context of one's own life, at least). The life of most people is far too repetitive. The reason "time flies" is because the same thing is being done every day, so that 100 days can feel like 1, since the sum of their varied experiences is hardly any greater. Strive to maximize your variety of experience.
In talking to some of my more adventurous friends in the last few days, they've told me heart-pounding stories of excitement and danger resulting from their travels in places like Beijing and Uruguay. But they got through, having pushed their own limits and learned a bit more about their own capabilities. In retrospect they are all thankful for these experiences!
Don't be cautious! Imagine the most foreign place you could go, and go there. Go to the unexplored places remaining in your own life.
Human nature yearns to be challenged and pushed to it's limits. People do not hike to the top of Mt. Everest for the view and a nice picnic...
Discard your reliance on material things! Be confident in your abilities to survive and overcome obstacles thrown before you. Go forth and venture! Don't need.