I always have a little chuckle to myself when I see people enter the gym with a newspaper. Maybe it’s just me, but I can’t train at the correct level whilst reading. I’m not saying you have to always ‘beast’ yourself but even if you are doing low-intensity fat burning on an exercise bike, you should be monitoring your heart-rate or speed… Training in the right zone is important and that takes concentration.
Also, multi-tasking is not very mindful. I believe in focusing on one thing at a time so I do it to the best of my ability.