Tips for going back to work and wearing a mask with asthma

I’m going back to work, and where I live they are making masks mandatory, and my work has also done the same. Since COVID started I managed to get by, I stayed home a lot and most of my errands were done by my boyfriend. I have asthma, along with severe nasal polyps and allergies that cause me to only breathe through my mouth (on the rare occasions I can breathe through my nose it’s stuffy)

I’ve been okay with wearing a mask the few times I’ve gone out, although there’s a few times I’ve felt lightheaded and I’m scared to go back to work. My shifts are 6-8 hours and I work at a fast food place and I’ve never gone more than 10-15 mins with a mask on.

Is this something I should mention? I’m worried if I mention it they won’t want me to come back and with everything going on I probably wouldn’t be able to find another job. I think I might just be over thinking it.