I realized recently I started reading books the same way a keep listening to videos on the background. It works for passing the time or unwinding a bit. For retention, mindfulness exercises (silly as it sounds) seem to work: taking a look at my environment and taking a moment to clear out distractions, stoping to think what is it I last read on that book (which is always harder then I expect), reflecting why I’m reading whatever it is I’m reading. Doing these things as little rituals tends to help.