I keep old paper coffee cups and their lids. I get 3-4 more uses out of them before they fall apart. Nothing like brewing your own coffee at home and walking with it to the station

“you can literally buy a thermos for the same purpose” I hear you say, but a thermos can’t be scrunched slightly and put in your pocket after its finished like a paper cup can. Plus there’s no worry if you lose it, because you know it’s junk