Focused Thinking

Ever feel like you can’t concentrate? Like the stuff you gotta do seems too much work? Even though your body seems fine? Perhaps you’re lacking mental energy.
You see, our brain is just like any part of the body- it can become tired if overworked and not given rest. So when you do anything that requires thinking- which is probably most of your tasks- then you spend mental energy.
Switching between tasks uses up mental energy, like pushing a trolley- takes a lot to get started, quite easy to maintain speed. When switching tasks, you mentally lay out your new task. When you switch tasks every 5 minutes, you burn all your energy and time just prepping for the next task instead of doing anything!
This also applies to thought switching. When your mind is like “I gotta do my English homework about literature. Hmm… in that anime, what was the Main Character’s backstory again? And what was on my Wattpad list… oh yeah, that fanfiction about cooking. I wonder how to make some trileçe cake?”, then good luck with doing your English homework.
Every time you shift thoughts, you need to spend energy to think about your task again. And since your task is probably boring or a pain, your willpower will be drained too. Your mental resources will quickly become insufficient at this rate. What’s the solution then?
Focused thinking.
Basically, keep thinking about one topic, in particular, the task you are doing. It may be tempting to think about other stuff, perhaps because the task is super-boring. Or, you’re afraid of losing the value of that other thought. Maybe you got a great idea for your next novel. Maybe you remembered you had to check your email/Whatsapp for your friend to contact you.
Note the thought on a paper or digitally, then return to your task/original thought. If you pause for less than 30 seconds, your mind is still devoted to the original thought, so you don’t lose focus.
An extension of this is rituals and plans. When it’s obvious what to do next (eg, dry yourself after showering), you don’t have to think about it. When it’s not so obvious (eg, which university to apply to), you have to think. And thinking uses energy, as discussed previously. Rituals and plans minimize thinking and required energy.
Rituals are a set of activities you follow regularly. An obvious one is before sleeping: bathroom, brush teeth, change into pajamas, get into bed. Rituals help you get needed tasks done without wasting mental energy, so use them as much as possible. An example: Before sleeping, I brush my teeth, plan my next day, and put my phone away. It's likely you already use rituals somehow- so learn to utilize them even better!
Planning your days with to-do lists also helps greatly. With a to-do list, you know your next task without having to think. Plus, these lists make you realize you have a ton of stuff to do today, so there’s no time to waste! Be flexible with such lists of course, but use them!
Even after applying these tips, there may be times you feel unable to focus anymore. Perhaps you're just tired. In that case, rest your mind. Don’t think about an exciting story scene or that nice girl you met last week- just blank your mind. Close your eyes if possible. This will rest your brain and eventually allow it to focus on what you should be thinking about. Some caveats: it's important to take breaks and switch your thoughts up if needed. You shouldn't switch every 5 minutes, but it's rarely feasible to focus on something mentally exhausting for hours.
I have personally benefited greatly from controlling and focusing my thoughts. I used to be rather unproductive even with an awesome to-do list system. I knew my next task, but I rarely felt like doing it! Now with focused thinking, I consciously minimize my mental activity throughout the day, so I have tons remaining for my productive tasks.