The process of experiencing the outcome (and the decision) as well as judging it and getting this visceral experience of "this was right/good" and its accompanying jolt of pleasure.
This process is costly and can annul or even contradict the emotional effects of the original action.
When the original action (say relaxing, paying pleasantly attention to a lick of ice cream etc.), is done for emotional effect, the emotional hubhub of the second order process of judging it, looking at it even, can be contradictory. Especially for small actions.
Avoiding such second order effects can be very useful.
PS. Mindfulness, letting go etc. Might partly want to get there.
Also, getting to this avoidance of second orders might not work forcefully, as forcing thought processes can cause contrary effects, as Daniel Wegner shows. That might be why meditation teachers say "gently"