One great idea from the book "Your Money or Your Life" is the concept of "real hourly wage." You probably know your nominal hourly wage, what your employer pays you. The book makes you calculate how much extra time and money it takes for you to make that hourly wage. First, figure out federal, state, social security, and local taxes and subtract that (around 42% total for Oregonians). Add in commute time. Costuming, i.e. work clothes. Transit costs, either public transit or auto payments. Money you spend due to work stress: drinking, expensive vacations or trips, gym membership, massages, etc..
Do your own calculation. What you will come up with, after all of that, is that your real hourly wage is much less, probably closer to 1/3 of your nominal hourly wage (remember taxes take out a huge chunk before you see anything). So if you make $30 an hour, you're actually making maybe $10 an hour. So when you spend $20 on a meal, you're choosing to spend two extra hours of your life working. If you spend $90 on a piece of clothing, you're choosing to spend 9 more hours of your life working. Reframing spending money as how you spend your life hours is powerful.