If you don't respect your money -- how much you have now and how much you can expect tomorrow -- you're setting yourself up for doom. This is also known as "credit cards." They're awful things that we should have never invented. They're financial Balrogs, born from us digging too greedily and too deep into a mountain of eBay crap and Etsy brownies.
New Line Cinema
"YOU SHALL NOT PASS ... and especially not with a 400 score."
Every month, at least, you should plot your spending. Why? Because it offers perspective. If your money has no purpose and you order a pizza here, take a cab there, you might find yourself looking at your bank account with a $100 balance, wondering where that other $300 you swore you had went. And you'll look over your transactions and confirm that nope, you were never robbed. You kept spending little bits and little bits and little bits, until you buried yourself in a hole where you can choose to not spend any money for the next week or rely on credit. Boo!
If you're old enough to make money, you're likely in a place where you can determine how it needs to be spent. You need this much for rent, this much for your phone, this much for Internet, this much for groceries. Do this every time you get money, and then, when you have leftover money that isn't absolutely, positively needed for a specific expense every month, divvy it up between having fun and saving. But make sure it all has a purpose.
For example, this is my "buy a new jar" fund.