I had HT 3yrs Zoladex (including couple yrs abiraterone, enzalutimide, prednisolone on trial) &RT, treatment finished summer 2018.
I was at least averagely fit, enjoyed exercise and all that, continued working mostly tho office job but think I sort of didn't work whilst having RT (only because work quite relaxed with me).
At times there was nothing I could do to avoid the fatigue, I'd often just fall asleep whilst reading and I mean properly asleep. It wasn't all the time and maybe it was worse last part of RT. When I could I always tried to exercise, gym, bike, windsurf, paddleboard, but obviously to a far lesser extent than I'd like whilst being fully aware that it was treatment having this effect and things will improve - and they did.
Peter