Practical Question RE Credit cards

I understand the goal of getting to "Cash Only", and see it's value. The question is practical. In practice, how do you get there? Especially these days with doing online purchases on Amazon and the like, how do you NOT use a CC to pay for things? How do you pay cash to buy gas? That's just two examples. Use a Debit card instead?

In fact, there are starting to be 'in store' merchants who actively discourage the use of actual cash.