I simply keep a manual tally counter by my side while reading and every time I catch myself reading mindlessly or my mind drifting away, I count one distraction. Similar to some forms of meditation.

Ultimately, you want to bring up the quality by minimizing the number of distractions per unit of time.

The good thing about it is that you actually build up your focus and concentration "muscle" (in prefrontal cortex) as opposed to amping up the volume alone.

I too got inspired by gym :)