If you are carrying extra weight, the stairs in most classes of RFAs will kill you. Even Royal complains about the stairs in the Bay Class. One Captain, now retired was particularly big and couldn't get an ENG 1 medical for more than 6 months at a time. A bit shit when he was expected to do 8 month appointments. He's a racing snake now.
The RFA may not fast rope from helicopters to deal death to the Queen's enemies but the RFA are not exempt getting a sweat on. If you climb obstacles like old people fcuk
(copyright Gunnery Sergeant Hartman) you'll suffer. Lose weight, get fit.