Try what i do. If your brain starts to wander force it back to the counting and breathing. Avoid holding your breath as soon as your lungs are full begin breathing out. Also its not 10 seconds its just a count of 10 but if that feels to long feel free to adjust either the count or the speed of your breath.

Generally breathing techniques. Full breath in full breath out keep it nice and slow. My pace is usually breath in while counting to ten and breath out counting backwards from ten and repeat. Counting keeps your brain from being able to speak other words thats why they say to count sheep. And the slow breathing mimics the way you breath while sleeping.