Taking action without changing thoughts

I recently came across Mel Robbins’ 5 second rule and absolutely loved it. I have been implementing it in my life in areas where my brain has lot of resistance in starting a task – exercise at home, writing my promotion document etc.
my question is , we are taught in scholars and by brooke that if we change our actions without changing thought we will eventually run out of the will power.

But often there is so much resistance in the moment and my primal brain really does not want to take action. My thoughts usually are “I don’t feel like it”.
Instead of stopping to do thought work and changing thoughts, I just count 54321 and do it .
I’m curious about what is really happening here. Am I taking action in spite of negative emotions ? How can I make sure that I am not using will power here ?
Looking for a way to tie Brooke’s and Mel’s concepts together.

Thank you