Try this to fill up your energy tank before extracting energy out!
Charging energy to your energy tank should NOT consist of activity of any kind that further withdraw energy from your tank, such as drinking coffee or energy drink, a long run, spinning, cross-fit, HIIT or boot camp. It should be rather something short, e.g. a brisk walk, a short nap, or when these are not possible just a little funny exercise right at your desk. See this one:

If you have no tennis ball at hand, place an other object in between the feet. Take a deep breath in through the nose, on the exhale through the mouth think about NOTHING! It’s not easy, is it?, thinking about nothing. If easier, just think about the air coming out of your mouth. Then raise your feet while squeezing onto the object in between and start swinging them left and right. Do 8 repetitions.
Try to schedule in these “tank toppers” every 90 minutes of work time. Your performance will thrive, you see.
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