If you have a decent credit card, they often can categorize your purchases and show you where the bulk of your money is going.
When I commuted, it was gas in the old 92 Cherokee.  16mpg driving 70-80 miles a day adds up.  Got better when I purchased an 03 Impala that got about 23mpg.
You mentioned bars, and depending on where you're at, that shit can be stupid expensive.  In my small local town, I could have 5-6 over 4 hours and walk out for under $15 including tip sometimes.  In the "city", that'd cost me upwards of $25.  Add in shots or any of that sort of thing, and you can get upwards of $40 pretty quick.
Outside of that, I tend to find things that I have a legitimate need for, things that'll save me money, good deals that I may not need now, but can't pass up.  I may walk into a FinishLine or similar store, and while not needing new shoes, see a pair I like at $30 instead of the usual $60+.  I'll buy them and cycle my shoes around (older ones become mowing shoes, working shoes, etc. etc.).
All in all, I don't buy that much anymore, as most of what I've needed, I've found deals on and picked up.  When I do feel the need for something new, I'll justify it and figure out how to make it work, or I'll keep and eye on the item and try to buy it when I can get a substantial savings at a given time.
And I try to keep my car situation completely paid off.  If I get laid off, I can always sell one of my vehicles for some extra cash if need be (wife and I have 3, so if we lose 1, we still can each get around without depending on one vehicle).
Last and certainly not least, I don't spend more than I make.