How did you afford to live on $5-$10 a day in developed countries? I'm guessing couch surfing for accommodation, walking or buses for transport, and cooking all

How did you afford to live on $5-$10 a day in developed countries? I'm guessing couch surfing for accommodation, walking or buses for transport, and cooking all your own food, but would be interested to hear how you did it. Also, which developed countries were the cheapest and most expensive to live in?