If you try to think in terms of the "now," it may be of some help. Here is what I mean by this. All we really have is this moment, if you think about it. The past and the future are fictions of our imagination. You have to get yourself into a mind frame in which there is no past, there is no future, there are no goals, there is just the joy of the moment.
I don't think this applies particularly to P.E., but to all things. You know when you reach a goal, there is usually a voice in our heads which says, "Is that all there is?" Ask any P.E.er who has reached his goal. He wants more, a thicker, longer dick, another inch, etc. There is a part of us which is never satisfied with our size however big our dicks get.
There is a certain emptiness, and then we make new goals. We need goals, for sure. But the thing that has sustained me through the last five years of P.E. is the joy of yanking my dick. I approach all things in this manner. I only have the moment and so I enjoy it the fullest.
Do you have one activity (other than P.E.) that you enjoy so fully, that it makes you forget about everything but that activity, including time, for sure. Sex, for example?
Listening to music? Reading a good book. For me it's swimming. Try to apply that mind set to your P.E. sessions. Don't count reps. Forget about how much time your are devoting to your session or any one P.E. exercise. It's o.k. to imagine yourself making a longer, thicker dick, but the point is to "hypnotize" yourself into focusing on the moment. Otherwise, it becomes boring and you will lose interest, like any activity.
Hope this is helpful.
"It's not the going but the getting there that's gotta be good."