Technology will eventually allow us to control our brains via cybernetics. If there is no technological blackout, and if the world doesn't end first, then we will incorporate computers into our brains to aid us. Unfortunately, I don't expect to see sufficient caution in this area, and we may see casualties of science. This is too risky of a proposition to be experimented with enough to make it safe, but be sure it will be. However, it is unlikely that emotional control will ever be a commonly accepted feature of computer enhanced brains. I also believe that these computers will make us lazy, and useless without computers.
The day will come when scientists can reprogram the brain so that one may simply say to oneself that they want no more stress and it will disappear. The day will come when emotional and stress management is easy, just say what you want to happen and your brain and body will comply.