The question describes your reasons to come here and improve your productivity but doesn't speak of any actual problems. We need you to try something or do some research on the topic, find problems implementing a productivity system, for example, or need a solution for a process that is currently not efficient enough.
An answer covering relaxation techniques, lifestyle and nutrition can't be anything but too broad. Supposing you get three very good answers, one for each of the forementioned areas of expertise, how would you pick the best one? And most importantly, how would it help others? Your question could have been answered in far more detailed ways if it was splitted in several questions.
If there was such thing as a technique exclusively designed to improve programmers' productivity, I guess your question would be ok. But the most discussed productivity systems here can be used by pretty much anybody because they can be adapted to your individual needs. You need to find what are you needs then ask your questions accordingly.
But don't worry too much about this. Your next question will be better.