I may sound retarded to most of you but abstinence is the best state of mind ever. Just not thinking about instant pleasure (fapping or sex) will improve your productivity. And in a couple of weeks you'll feel extremely calm and comfortable. And this doesn't apply only for fapping, you could abstain from alcohol and other poisonous activities.
The longest I've abstained from things is over a month, however for me I'm unable to concentrate without releasing my sexual energy. I get so obsessed about it that I can waste hours just fighting the thoughts. Whether it's through NoFap, prostitutes , Tinder or picking up beautiful women off the street.. there needs to be a release eventually for some people.