Want to stay current with Arthur’s writing? Sign up to get an email every time a new column comes out. If you feel you are struggling to stay on top of things and are worried about organizing your time and being productive, the internet offers hundreds of aids and techniques such as virtual assistants and apps that make to-do lists. But if you find yourself more and more distracted and harried, struggling to pay attention to what really matters and baffled by how whole days seem to simply disappear, you might be missing the single most effective way to free up time and focus attention: saying no more to all the demands bombarding you. This is more than just a way to increase your productivity. Psychologists have shown that the feeling of being harried and having insufficient time because of busyness is linked to less happiness. Almost everyone knows the sensation that comes when commitments pile up and deadlines bear down. A seemingly innocuous yes to a request is just one more thing added to …