On the Workout screen. To have the ability to customise your 4 (or even more) options. Instead of calories I would like to put Steps. Or Cycling Outside Distance. Or Add more options so I can compare more data as simply as swiping left.

Then I think the title "Workout" would need a name change. As this data feature is more then just Workout. It could be called Activities. And then you could bury deeper into it and have custom catgories such as Walk, Running, Cycling, Sleeping, Water, Hiking, Swimming weight etc etc. Cheers.