For many years I have heard runners talking about timing all their runs. This is a big mistake. Anytime you time yourself, you are putting yourself on the clock and with that you will for all intents and purposes probably end up running too fast. Now running fast is a good thing, but not all the time.
Running fast everyday will ultimately leave your body tired and run down. When training your body needs time to recover, which normally takes place at night when you are sleeping, but when you are training hard you need to give your body that little extra help by not running fast. That is why you will also hear runners talking about their “recovery runs”. These are runs where you run slower than normal or running as you feel.
My personal advice to better help you run as you feel is to leave your watch at home.