From the book Stumbling on Happiness:
When predicting feelings of something, making a decision based on the 'gut feel' had advantages in accuracy.
Prefeeling allowed nonthinkers (make choice quickly 'from the gut') to predict their fututre satisfaction more accurately than thinkers (think logically about why they thought they might like or dislike) did.
The reason could be that making someonet think about reasons, made them think about what they knew about the person asking the question or what seemed responsible.
When people are prevented from feeling emotion in the present, they become temporarily unable to predict how they will feel in the future.
One limit to prefeeling, however, is that the body confuses current feelings with a prediction. We do this with images (hard to think of a song while listening to a song, in fact, we will plug our ears to mentally 'listen' aka imagine a song). And we know we are doing it with images. However, with feelings, we confuse the two.
People will confuse their current feelings with how they will feel in the future.
One example is if you are feeling crummy right now and asked to imagine a future event, you will imagine the event as crummy. If you are happy right now, you will imagine the benefits.
[If] you've had an awful day...you may mistakenly attribute feelings due to the misbehavior of real pets and real appliances ("I feel annoyed") to your imaginary companions ("I don't think I'll go because Nick always ticks me off.").
Basically your current feelings muddle your evaluation of feelings when imagining something.
We cannot feel good about an imaginary future, when we are busy feeling bad about na actual present.
I would take an exception with the statement because, well, that is the promise of meditation. And actually, the 'present' described there is really your mind dwelling o the recent past. I posit that if you imagine terrible events in your past, or dwell on them too, and you were asked to predict future emotions, you might have the same reaction.