Mine started all of sudden around the 52-53 ish mark. It now seems to have a mind of its own. I have no idea on how it is going to perform - it is either too quick or I can't keep it up for very long even though my attraction to my partner has not declined.
Thankfully to this hobby, over time I've felt that I manage to gain the skills and confidence of an amateur porn star but now, I've reverted back to being school boy on his 1st date. It can be very embarrassing, humiliating and crashing blow to the ego especially when hobbying.
I have tried the blue pill. In my case, it only marginally helps. Even with that aid, for me it still has proven to be un predictable.
I am in above average shape for my age, however I do take Blood pressure pills. I was taking this long before ED started. Originally I thought that daily stress was the main culprit. I have also tried Ginseng, Maca etc.
I have not thought about iron that was mentioned above so maybe I will give that a try.