I do a zero-based budget monthly, where I precisely account for every dollar coming in and going out. Some of the categories in my budget (anything I buy in person) are designated as "cash" - every paycheck I withdraw enough from the ATM to cover the next two weeks worth of cash categories. These are then distributed into envelopes per category.

All of this leads up to my answer: I carry around personal allowance (budgeted for!) in my wallet at all times, and extra cash pulled from the envelopes when I'm going to buy something that day.

(When I end up using my card for a cash expense, because I didn't anticipate needing to buy something that day, the cash goes into a separate "Return To Bank" envelope. The next time I would withdraw cash, I just take what's in that envelope first, and then withdraw only what I still need. In other words, using my card is merely a loan taken out against my next cash withdrawal.)