It's been pretty well established now that multitasking isn't really a thing. Answering emails while studying for your finals just means you're doing both of those things poorly. At best, you're at 50% productivity with each activity. It saves more time in the long run to only answer emails, then when you're done, only study for your finals. I guess you should probably do it in a different order though.
This runs directly counter to my wish to be doing everything at once. I like to think that my pursuits are noble enough; I'm trying to finish Susan Wise Bauer's The History of the Ancient World, while teaching myself Spanish, while learning how to code, while trying to stay fit despite a shoulder injury.
Tension comes most when I have a lot of free time. There is an effectively infinite number of cool things in the world for an aspiring dilettante—a Jack of Some Trades—to try, but since we can only do one thing at a time, it seems imperative that we do the "right thing", which leads to a lot of time wasted on flitting between one project and the next, afraid of committing too much to one thing because there will be (∞-1) things you are neglecting when you do it.
This is an emotional response, and one I have frequently. I know I am not alone in this. The important thing to do is to recognize that ultimately this desire to do everything is itself a form of inefficiency. If we really want to be productive, we must cultivate the skill of committing fully to the task at hand, and detaching fully from it once we are done with it.
Ultimately, this is the idea behind my Year of 12 Habits. Commit fully to the habit, and if it sticks after a month, great, and if not, there is something else for you to do. I'm happy to report that some of my habits have stuck since January. I'm certainly not 100% on any of them, but by focusing on one thing at a time (on a macro level) I've been able to literally change my life for the better.
All we can really do is adopt that process and refine it. But even if I didn't improve beyond today, I am still a better person than I was five months ago.