Why aren't double chin exercises possible?

First, it is important to keep in mind that there is no such thing as loosing weight in a certain spot aka “spot reduction”. The human body likes to lose weight in an even manner, for the most part. So, unfortunately, exercises that you might be doing specific to the chin and neck region will do nothing to lessen the amount of fat in that area. If you are you are on a rigorous exercise program involving all areas of the body, with both cardio and weights, there is a good chance that the fat in the area under the chin will lessen (and other parts of your body will improve as well, another benefit of exercising!). That being said, if you are sick and tired of exercising, and have not seen much improvement, I would recommend that you see a board certified plastic surgeon to consider submental liposuction. Good luck!
 

Double chin deformities can
adversely impact facial aesthetics and for this reason patients frequently seek
treatment of this condition. This condition can be caused by abnormalities of
the facial skeleton, loose skin and neck fat collections.  Unfortunately, all of these problems
require surgical intervention. 
Neck exercises wouldn’t impact the underlying anatomic problem.

For this reason, patients with
double chin deformities should consult a board certified plastic surgeon.  This surgeon should be able to
formulate a treatment plan that’s appropriate for this
problem.

There are two main layers of fat in the neck;

The fat under the skin, which will fluctuate with weight gain or loss.

The fat under the muscle layer- the subplatysmal layer, which has been shown to be there even in starvation victims.

Working the muscles out will only cause the platysma muscle to be come more visible and contribute to the bands in the front of the neck.