It's not too late to change course. Just believe that you can, and start working towards doing things differently. Quit drinking. Get your education locked in. Start your career. Save ten percent of your income in a tax-deferred retirement plan. Live modestly, eat well, stay active (a sport is a good idea), be good to yourself and others and good things will follow.
It's not too late. You have virtually all of your adult life ahead of you.
Your sentencing may go better if you have the makings of an inspired turnaround to tell the judge about at the hearing. So there's some incentive to get started ASAP.