The quickest and easiest way to stay grounded and centered is through your breathe. You can do this exercise sitting, lying down or standing up. Focus your attention to 32 inches below the earth and with a nice, comfortable inhale think of the breathe coming up from the earth into your feet, up your legs, through your torso, up through the neck, head and up to 32 inches above your head. Now, with a nice steady exhale let the breathe come down through your head, neck, and out your shoulders, arms and hands. Repeat this breathing pattern, making each inhale and exhale as long as is comfortable. Anywhere from 4 to 6 seconds on each inhale and exhale is adequate.
If you are new to breathing exercises this may feel a little uneven at first, but you will quickly get the hang of it and will soon find this exercise to be a calming and relaxing experience.