1- 我會上載一段關於健身訓練6個月的記錄片 We can understand if you say it like this , and we can say it in other ways:
2- 這一段記錄片是關於健身6個月的訓練. You can say it like:
3- worship the iron = 健身朝拜
If you say 健身朝拜, we may not understand, you can say 鋼鐵信仰（I search it on the Internet, here's a video named worship the iron. It's chinese translation is 鋼鐵信仰. I think it refers to someone who likes fitness very much)
You can consider my answer as a reference, because I speak Mandarin, not Cantonese. There might be a little difference.