I hate my job ( entry level )

I work at a carpark and has a drop off / pick up zone and i just try to tell the people in the cars politely to just please dont stay for more than 3 mins and the people in cars verbally abused me as its a inconvenience to them. Im just trying to do my job . I just finished high-school and taking a gap year before uni to save up, this is the only job i have found as it is a very bad job market at the moment, the job has me waking up at 4am and have 10-12 shifts by the end of the shift i cant walk properly as we are not aloud to sit down until break which is only 2 30 min breaks. I dont know of im being a bitch but Im really starting to hate it and its the only job I have as everywhere i apply to thousands of other people also apply, when i get home i cant even do the stuff i enjoy because im so tired after the 4am wake ups, can someone please tell me what to do, i just feel really unhappy or if im actually just being a puss puss.