Just because you have money currently in your possession and you've paid all of your bills for the month does not mean you have to or should spend the rest of your earnings. Leaving a portion of your money for another day will be the difference between you staying in debt, getting in debt or you carving out a great financial future for yourself. Build the groundwork for you to not feel like you are living paycheck to paycheck.
Live under your means. Put a portion of your pay away in savings. Students, put it away in a savings or CD account. If you're knowledgeable enough or have a knowledgeable and reliable teacher or mentor, look into opening a Roth IRA. Its never to early to start saving for retirement. Or do a combination of these suggestions or more in areas you understand. Just make sure you are not spending every dime of your pay.
Don't let the knowledge of the money your have burn a whole in your pocket.