Weight and space are the enemies of the long-term traveler. Whenever a friend hangs out and watches me pack my luggage after I've been in one place for a while, they're always amazed at how I sit and analyze whether to toss or keep any given piece of gear.
For instance, the USB-to-power-outlet adapter for the Amazon Kindle and the iPhone works for both of them. So, I threw one of them out. A friend was with me when I was packing, and he said, "Dude, why don't you keep both? It's tiny..."
And yes, it is tiny. But I'll probably make 80 decisions like that in a given year, and if I default to "yes" on all of them, that adds up to quite a lot. (Eventually, I threw out the USB-to-power adapter entirely, and I just charge both devices from phantom power on my laptop now)
This gets tricky, though, when you have something that's somewhat valuable but also bulky. When I got a new laptop, I now had two power cords/bricks. I've had a pretty nasty run of breaking power cords/bricks for whatever reason - just one of "those things," I guess - so I was sitting and figuring whether to pack both.
Eventually I tossed one.
It's easy enough when you've gotten things for free. I rented a room in Taiwan for a while, and my roommate left back to Europe with a lot of his things in the place - and then said he wasn't coming back. This was the last month of the lease, and he said if I cleaned the place, I could have whatever I wanted.
So I stocked up basics - I had some extra space so I grabbed a nice towel, some soaps, things like that. He also had a bottle of cologne. Now, I like cologne. I think smelling nice is nice. I used to wear Azarro Chrome back when I was less on the go. But cologne is heavy and takes up space, so it's one of the first things to be gifted away when I eventually leave.
But again, for whatever reason, I had extra space in Taiwan, so I grabbed a bottle of cologne and was wearing it for a while. Later, I had space constraints and gifted it away to a friend in Vietnam.
No problem, no stresses there.
But it's funny, when you purchase something, the attachment levels go up, and it becomes much harder to gift/toss things after that. For instance, you get a pair of shoes but they turn out to not fit well. If you got them for free, they're easy to toss in the trash or gift on. But if you paid a fair bit for them, the decision becomes a bit harder.
It shouldn't! It doesn't matter how much you paid for gear once you've got it. Gear should be judged on its usefulness to your life, and the costs of carrying/maintaining it - in my case, space/weight is a major constraint, but also the general upkeep of having more stuff in your life.
So I'm trying to mentally discard the price I paid for things after I've got them. By focusing on the past price, which is a sunk cost, it's made lug around stuff that wasn't very useful to me. This increases my traveling weight/space (a pain in the neck when boarding and unboarding trains, means my bag moves from carry-on size to must-be-checked size, etc) and also has an opportunity cost - I can't get other things. And then there's the mental cost of having more stuff.
That sucks. That's made my life very slightly worse. So now, with gear, I'm trying to remove price paid from the consideration and just think about how useful something is to me and how much it costs to keep having it. This leads to clearer thinking, better decisions, and ultimately less junk.