Multitasking contributes to stress and lowers productivity. Whereas you think that by doing a few things at a time you get done more, the mental energy which you need to switch your mind between the two things takes its toll on you. Plan your day in the morning and follow task by task. Check emails once an hour instead of immediately as they arrive. And reduce phone usage (especially apps and messages) to the break time, not to get distracted. You’ll finish your tasks faster, and your mind will appreciate a more focused approach.