The human tendency to assume that time is on your side is one of the most expensive cognitive biases available and it costs people everything eventually. You are young. You are healthy. Things are not that bad yet. You will deal with it later. Later is doing an enormous amount of work in that sentence.

The all nighters and the drinking and the not moving and the eating whatever you want and waking up fine, that is not evidence that you are exempt from consequences. That is evidence that consequences operate on a delay and that the delay is currently working in your favor and will not do so indefinitely. The body keeps the score of EVERYTHING you do to it and everything you fail to do for it and it presents the bill on its own timeline which is almost never when you expected it and almost always when you are least prepared for it.

This applies to everything simultaneously and with equal urgency. Your health (start now, before anything is wrong, because prevention is exponentially cheaper and easier than treatment in every possible sense of those words), your finances (the money you do not save at twenty five is not just the money you do not have at fifty, it is the compound interest on that money across thirty years of growth you will never recover), your relationships (the patterns you establish early are the patterns you will spend years trying to undo later if you do not address them now when they are still flexible), your career (the credential you do not get, the skill you do not develop, the connection you do not maintain). These have costs that accumulate invisibly until they are suddenly very visible.