When we do things for the sake of finishing them, or being done with the task, we tend to life in the future. Our mind is focused on some concept but not the now.
This creates two unwanted side effects. For one, we enjoy the things we do less. It seems to be only a necessary step in reaching some place we actually want to be.
And secondly we train our mind to seek happiness in some imaginary future. And we repeat this behavior over and over, so that it becomes our new normal.
At one point we constantly look for some future in which we hope to be happy. This doesn't have to be a conscious process. You may not even be aware of this mental habit.
What is the alternative? Slow down your mind. Catch it when it looks for the future. Catch it when you do want to do something fast in order to be in a happier place when you finish.
Instead you can experience whatever it is you are doing mindfully. You can do things quickly if that's what you like. Maybe you enjoy the challenge. That's fine. But constantly rushing through your life to get somewhere else will keep you from ever arriving.
Instead you should train your mind to be always present, regardless of what it is that you are doing. Regardless of the emotions you feel. Let them come, invite them in, all of them, let them pass and do not hold on, to none of them.
Just be aware that in this way you are building a favorable mind structure. One that is more likely to lead to a happy experience of life.
Maybe you have noticed how in japanese culture they seem to do everything they do with a certain grace. Even the so called "bad" jobs they do with pride. Because their culture generally does not teach them to finish quickly, but to produce the best work they can.
This shifts the focus away from the future and to the present moment. In order to produce flawless results, you need to concentrate on what is right in front of you.
This is some good advice to follow. For your work and your whole life. Live a high quality life, not a fast-food-style life.