[jere]

I don't think those count as "moderate to vigorous" exercise, at least for most of the time you're doing any of them.

[bryanlarsen]

The study specifically includes walking in their list of exercises. You probably do want a mix of exercises -- 90 minutes of vigorous exercise a week is a standard recommendation, but 10h a week of vigorous exercise is probably contraindicated for the average 57 year old in the study.

Walking is good exercise for anybody who is out of shape.

[Fire-Dragon-DoL]

Walking as moderate exercise is not "just walking" though. You need sustained speed

[nickburns]

Consider the speed/vigor with which one does something, whatever it might be. It can be quite the range.