I take wonderful care about my belongings because I really care about them and take extra care to make sure they won't get damaged. I feel like crap for a long time if I break something.
I'm exactly the same. If something gets damaged, either by me or someone else, it'll be on my mind for a long time until I can finally come to terms with it and just move on. But I love taking care of my things, and especially other people's, I wouldn't dare be careless with someone else's belongings because I'd understand the frustration of anything unfortunate happening. I've known many people who don't take care of borrowed items, or even just handling something that isn't theirs, and it really drives me nuts.
I'm prone to misplacing small things sometimes though, like my tablet pen or charger cables. Sometimes I just forget where I've put them but they're never far away.
I take far better care of my material possessions than I do of my own body which I feel like says an awful lot about me as a person lol. The only thing I've ever had break was my previous phone on a night out during which my intoxicated self thought it'd be a cool idea play around on a swingset in the dark... needless to say that didn't end well!