[madg]

Look at the brain as a dog that can be trained.
It takes a bit time and forceful practice, but it can be done.
Feel sad? Force yourself to feel happy and keep doing what you doing.
Feel stressed? Force yourself to feel relaxed and keep doing what you doing.

PS. It sounds a bit like conspiracy, but keep in my mind, there will be always something from authorities that will force you to feel bad, sad, stressed, if you're not filtering the outside inputs. Roughly that is it. Forceful practice 24/7 for 2-3 weeks and your dopamine will skyrocket and you won't give a damn. Just keep moving.