My GP charged me £25, he included that I also suffered from Haemochromotosis, a genetic disorder I have had all my life and has never stopped me doing anything, including marathon running, boxing and rugby to quite a good level. Admittedly whilst a few years younger.
They declined my membership citing chronitic medical risk due to combined effects of the illnesses. Another gym welcomed me with open arms a few days later and accepted the same letter I am pleased to say.
Three weeks later I needed a further letter for my holiday insurance. Guess what, another £25, first three paragraphs identical, the forth changed by the inclusion of a bracketed comment to include the medications I needed to carry with me. I needed three copies, he tried to charge me an additional £1 per copy. I was called unreasonable when I told him to keep the copies.
I will say in everything else he has been brilliant and did offer to speak to the original gym, I decided as they didn't want me I didn't want them.