Don't find my birthday depressing either in age or occasion. Not yet, anyway. Turned 29 last month but I don't feel (just under) a year away from 30.
Given the culture I grew up in there's always pressure to have or do certain things by a certain age (kids, marriage, house etc etc). I literally couldn't give a fuck what society or (extended) family said I shouldo do by certain age so it was always a proverbial 2 fingers up at that.
I quite enjoy my birthday - always with family and never at work, usually plenty of days off after to lead in to new year, too.