Feedback required on how to broach subject of potentially adding a WFH day

Hi team,

Looking for feedback from HR professionals. Essentially my current role is 5 days in office. I have been dealing a myriad of health issues (cancer, severe joint point which causes me to walk very slow and get very stiff to name a few).

I was wondering for guidance on how best to broach the subject of gaining a wfh day or two purely to assist with my health issues. The office has no lifts or anything so due to joint and physical pain, i am having to literally drag my body up two flights of stairs multiple times a day, which is causing more damage to my joints and body. Apparently alot of the higher ups are very anti-WFH. I've built a good relationship with my director and he's aware of what's going on with my health as I've had to take time off work for appointments and feel comfortable with approaching him about it but just need help with how best to and whether it would be good to include medical certificates or whatnot.

TLDR - 5 days in office, due to health issues am constantly drained to the point I physically cannot get out of bed on weekends, guidance needed as to how best to broach the subject of wfh.