Here is a good way to focus when your mind gets distracted.
Alternate Nostril Breathing
Using your right hand, place your thumb against your right nostril.
Inhale deeply through your left nostril.
Hold your breath and close your left nostril with your index finger.
Release your right thumb and exhale slowly through your right nostril.
Repeat, inhaling on the right and exhaling on the left.
Let each breath become longer. Feel the calm and balance.
Office Yoga: Simple Stretches for Busy People. Darrin Zeer, pg 74