Carrying cash usually isnt a good idea. I am far more prone to spend cash not to mention you could lose it.
My spending was out of control a number of months ago. I was spending upwards of 7k on who knows what. I bought microsoft money, used a single card for 2 months, and synched MS Money to that card. It analyzed my spending into categories and allowed me to see exactly where each and every dollar went. Quite helpfull.
Additionally, I have $153 dollars per pay put directly into my IRA (153 per pay yields 4k/yr which is the max contrabution allowed) On top of that, I have a sizeable amount taken out of my checking account (to which my paychecks are directly deposited) and placed in various investment accounts. I never have to write a check or think about a thing.