Do One Thing Well
James Clear, author of Atomic Habits, sends out a weekly newsletter called 3-2-1 Thursday. This newsletter consists of 3 ideas from him, 2 quotes from other people, and 1 question to ask yourself. The newsletters take about five minutes to read but take even longer to digest and apply to your life. I stumbled upon a simple quote in there that has made a profound impact in all areas of my life.
It's a quote from Thomas Mitchell on productivity:
"It is wonderful how much work can be got through in a day, if we go by the rule - map out our time, divide it off, and take up one thing regularly after another. To drift through our work, or to rush through it in a helter-skelter fashion, ends in comparatively little being done. 'One thing at a time' will always perform a better day's work than doing two or three things at a time. By following this rule, one person will do more in a day than another does in a week."
This applies not only to productivity but for learning new things. I was recently practicing chord inversions for the E Major chord on the piano. I realized that there were two ways to practice it. One way is to go fast through the entire progression making mistakes throughout the way. The second way is to practice the first part of the progression (E Major to the first inversion of E Major, then back to E Major), and only after you can do that with some proficiency (eyes closed is the target I aim for) you move on to the next part of the progression - E Major (I) to E Major (II) to E Major (I).
This applies to other areas of life as well, if you are training Jiu Jitsu, practice one thing you want to improve in class. At your job focus on a single task for the day even if you have thirty different items on your To Do list. This will lead to faster results than trying to improve on multiple areas at the same time.
Focus on one thing, and do it well, only then move on to the next thing.