Interesting thing. Actifit made my "Sunday lazy Sunday" into let's go out an walk.
It gave me a chance to test the app bug I mentioned earlier. It definitely isn't a feature, but there's still a chance of faulty phone.
Anyhoo I can't consistently reproduce the bug with normal use (when my phone is in the pocket or a bag) but, when I carry it in hand with screen turned on I've noticed the app will stop counting if you auto rotate the screen (turn it to the side and back upright).