Try this. Think about a specific point in your working day tomorrow, a point when you think you will need to be able to think on your feet, make good decisions, and relate well to people. When you have identified the point, allow yourself to really imagine it as if it were happening right now. See it and hear and feel it exactly as you will tomorrow (or just pretend that you are imagining it that vividly). Experience it, then come back and continue reading.
Now imagine a time when you were very young, a time when you were completely wrapped up in playing. It will take a minute or two for a time like this to come into focus - but you have memories of being a child and spending whole days playing with complete imagination and wonderful concentration. You have memories of being so caught up in your play that the rest of the world seemed to fade into the background. You have memories of thoroughly enjoying a day as you played with energy and enthusiasm. When you have a really clear picture of a time when you thoroughly enjoyed playing, come back and read the next paragraph.
Because you have focused on each of these experiences while reading this, your brain has already begun to form connections between them. You can make these connections deeper and more reliable this way: first imagine a large tv or movie screen in front of you, and cover it with the picture of you at work. In one corner, put a small picture-within-the-picture of the time when you were so enthusiastically at play. Let the small picture become bigger and brighter and more colourful until it entirely covers the picture of you at work. Repeat the process faster and faster until it becomes automatic: whenever you see the picture of you at work, you immediately start to cover it with the picture of you at play.
Make a note in your daytimer or calendar: before the day begins tomorrow, think about the same point in your working day. Notice how you feel about it: you might even want to write a note or two. Then get on with your day at work. And be prepared for an enormously productive day!