Usually, it starts somewhere around the age of thirty when most men are passing their physical peak years and their systems begin to slow down. In fact, the vast majority of men all over the globe with deal with some version of it at some point or another. That story is far more common than most men think.
And then you might remember that there was that time when you simply had trouble getting that rock hard erection that you would normally get and you chalked it up to stress or something else unrelated. Sure, you still liked the idea of it but that overwhelming desire to get it on just wasn't quite as strong as it used to be. At first you didn't even notice it was happening but it likely happened starting with a small but definite loss of in sex. You loved everything about from the anticipation of it to the erection that signaled the start of it to pure joy of the act to that final explosive orgasm that finished it.