You Have to Feel It

Smart move by Mitchell to omit (in his opinion) _why_ you have to feel it, as evidenced by the spread interpretation in the comments.

In my opinion, you have to “feel it” in order to do your best work.

However(!), and also in my opinion, you shouldn’t always strive to be in a position where you “feel it”. While it is important to spend most of one’s life feeling it / doing their best work in order to be fulfilled, the hazard of insatiably “feeling it” is that you can much more quickly burn out.

Working with passion fuels a level of intensity and emotional involvement that can take a while to recover from if you don’t get the result (read: success) you desired.

But yes, you do indeed mostly have to feel it.

Feeling some moderate positive emotion as a result of your work is not incompatible with 9 to 5 work.

The bigger problem is usually the opposite: nagging negative emotions, feeling annoyed, feeling contempt towards some parts of the work that one is bound to do. These emotions are unbecoming, so the psychological defenses hide them, as if there's no feeling at all. This is what "mind-numbing" work often is.