Ibuprofen and Scholl Gel Insoles help a lot. I always used to tell my new hires the first day was the worst, then on the second day I'd tell them the second day is the worst because you're still tired from the first day. Then they'd realise every day of the first week or two was worse than the previous days. Give it a few weeks and you'll get used to it. Don't quit a week in, you've already got the blue badge so you may as well stay at least until the pandemic is 'over' which might also be never.
The masks are probably the worst part of the job at the moment, not just because your face is going to be constantly warm but also because nobody seems to know how to wear their masks so you find yourself judging them silently (or loudly if you're one of my friends).
Also, buy these first or get better shoes - some people like me get ruined by flat soles. Vans for example kill me, but trainers or anything with a slightly raised heel, I'm fine.
these work well for me. I go through about 3 pairs a year but it's better than foot pain and blisters. I have a pair in my safety boots but I wear them so little they've barely started to wear down