When I was a student on no money we used to hang things we wanted to keep cool from plastic bags out of our windows.
I have been without a pot to piss in, and I am still not well off now, though my lot has improved somewhat. You can make things work, even in tiny flats with tiny spaces and shared kitchens. I've done that and still eaten well, even with a baby and young toddler.
Maybe we need to make a thing out of either asking the older generation for their habits when young, or buy the many books that now appear in charity shops on how to keep a household in the 1950s (the era before fridges were a thing in every house and before convenience food took off in the 70s).
Food is just one example, but mending things is another. I had the numbers come off an old watch (almost 25 years old, in fact) recently. Brought it to a local watch repair service, who took the thing apart and mended it - for free. Another service wanted me to pay £200 to get it sent away and all sorts done on it or buy a new watch to the tune of £140. It took the guy 10min to fix the watch and it works beautifully. I mend holes in clothes, use rags for cleaning or making soft toys or blankets for the kids, repaint old furniture to make it more modern, repair jewellery and mend what has broken in the house unless it's completely beyond my skill. Youtube and HowTo Wiki are my two best friends in that regard.
No one taught me any of this. Not cooking, not sewing, not furniture upcycling, nothing. I also work 60h weeks, so I'm not even particularly flush with time. But needs must, and with that I do my bit for the environment and save money.