As Gary Craig says, EFT works better when we are tuned in. In my experience I have found that to be very true. It can feel like we are going through the motions if we are not tuned in or associated with whatever we are tapping on and we certainly don't get the movement and shifts that we do when we are tuned in and really feeling what needs to be felt.
The reasons for not tuning in can be many, not feeling safe enough 'to go there', being dissociated and so on. Tapping with someone else who is able to help you access what you might not want to, is invaluable. In essence it is the ability to not shy away from pain, to embrace it instead, knowing that what we avoid grows bigger and more painful.
Ronald Ruden writes about EFT "It is interesting that this inhibition occurs only when the animal is in an activated state", in other words, being tuned in to the disruption enables us to dissolve the disruption. EFT is very powerful when we are tuned in.
Ruden, R. (2007). A model for disrupting an encoded traumatic memory, Traumatology 13: 71–75.