I have those voices in my head too!
I argued with myself all the way from work to the gym at noon about all of the other errands I could run, or whatever.
I could have come up with 10,000 excuses to NOT workout, but in all reality, they were all things that could be done later. So, I went and worked out, and felt much better after, which I knew I would!
On the drive, I had one voice, saying, "you could go do a or be or c." And I had the other voice going, "it's one lunch hour workout, the other things can wait, this is priority!" "You know what is right."
It's still a struggle some days.