I found out this little tip completely by accident. Well, not quite accident, but I was ordered to NOT look at the watch. I turned the garmin screen to the time of day instead, then looked at the data afterwards. I was amazed.
In an intervals run session more recently this amazing breakthrough was reinforced to me again. I programme intervals into the garmin as distance steps, because I do not have a running track anywhere near me. I programmed in my intervals, my rest steps, then off I went.
I ran the session on RPA (rate of perceived exertion) rather than based on the time. I found I was able to run faster than if I focussed on time, pace, or some other external statistic.
If you focus on the watch, and the time that it is or might be reading, rather than your running (or cycling, or whatever) then think for a second, what are you not focussing on?
Re-focus your mind and effort onto the physical activity that you are actually doing, your form, your breathing, your effort, and you WILL surprise yourself. If you concentrate on the time, or the pace, your own limiting beliefs will create a barrier, when you look at the numbers and associate them with either too easy, or impossible, or whatever you are thinking.
Discard your watch. If you cannot do that, then switch the screen to something else, some other data that has less meaning. Set the watch to beep or vibrate as your cue to switch pace, and focus the entire time on yourself.
Only look at the data afterwards. See the information as a learning opportunity, and decide on your RPE goals for your next session.