I'm very disciplined about paying off my credit card every month, which means I have a fixed total budget that I refuse to go over. A part of that I dump into cash in my pocket for beer and sushi and whatever doesn't accept credit cards, and the rest I set aside to pay off the month's credit card bill.
The effect of this is that I have to keep a running ballpark tally of how much I have left in the credit card pile, and since I've conditioned myself to be deathly afraid of going over, I always estimate conservatively, and I inevitably wind up with a surplus that I dump straight into savings and never touch again.
Why a credit card instead of a check card? Because the credit card company pays me that 2% for free, because if it gets stolen it's the credit card's money at risk and not mine, because if an emergency happens I have the flexibility to break my rules, because it establishes a credit score that I can parlay into lower interest rates when I want to buy a car or a house later.
I think the advice to not have a credit card is pretty terrible, actually. There are so many benefits, and as long as you have a little self-control, pretty much no downside.