First of all, I stopped eating out at work, I bring lunch every day now and that is saving me a TON. I never realized how much I spent eating out or ordering out at work every day!
2nd, my change jar is filling up FAST! I figure there is almost $300 in there, maybe more. No matter what my total is I only pay with paper moeny and the rest is for the change jar. If the total is $4.35, I give the cashier $5, the rest goes in the change jar, even if the total is $10.03, I give the cashier $11 and the rest is for the change jar. I also throw in any dollar bills that I find in my pockets or in maybe a side pocket of my purse, ect..a couple of "found" pocket $5's have made it in to the change jar too. The only thing I don't put in the jar is pennies. I keep a bunch of pennies in my wallet so if the total is $2.52, I give them $3.02 so I get two quarters for the jar. Of course the jar isn't going to pay for my trip, but it's going to be nice for food and spending money!
Another thing I do is leave my ATM card at home. That thing can just be too tempting sometimes!