yeah man just enjoy the day and indulge in things you normally wouldn't. Buy those cookies, get the chocolate milk. Maybe fill up the whole tank if you have a car.
No money? Spend some time walking around and enjoying the silence for what it is. You don't get much of it once you get older.
All in all, just make sure no one can bring your day down over some insignificant shit.
I have a job interview that I'm pretty much made for and my dad borrowed my keys just to lose them. I have no way to get there now. This was my ticket to moving out again. They've been doing this stuff since I turned 23.
Just don't let anyone have a say in your enjoyment and you should be fine. Don't depend on anyone else to celebrate if you think it's worth it. I don't celebrate birthdays anymore.