Life pro tip: fight lifestyle inflation/creep. Use all the shampoo. Be conscious of waste. Don't take it to "frugal jerk" levels but just keep in mind that you have to earn every dollar you spend.
At some point, you'll probably be making more money. People tend to choose to take this opportunity to also spend more money. Keep this to a minimum. Do you want to retire in your 40s or in your 80s?