I think about this when I run or bike with my husband. He does like to think about work and talk when he rides/runs, and I like to think/talk about anything but work (or nothing). He uses that time to solve problems, get his thinking muscles going, I use that time to NOT think and let my subconscious work on the thinking muscles thing for later. Nothing wrong with either approach, it's just... different. I do love spending the time with him, though.

Fortunately (I guess) for now we don't have the same fitness level, so I do my solitary workout and then run/ride with him (or vice versa - with him, then alone), so I get to satisfy both requirements. If we were at the same fitness level, we'd have to compromise a little - talk about thinking things but not work, travel in opposite directions, plan different workouts on different days so we're not both doing the same workout at the same time, whatever.