U will get used to it soon.

shoes with good comfy arch, or a posture brace from amazon (not sure which one my co-worker got but they said it's great)

if it’s your lower back, stretch your legs before going to work! stretching your legs can help with back problems, i do a straddle and stretch to both sides and the middle, also a sitting pike position, feet together in front of you and touch your toes, also the butterfly stretch (idk if these are common terms but u can google it for a picture)