The Gym at Rhosgobel

It's probably time to move up to walk 30 seconds, run 30 seconds or walk 2 minutes, run 30 seconds for half an hour, gradually increasing the length of the running part until you are running the whole thing. And by running, I mean a dog-trot or jog, not sprint. You need a pace barely above walking until you get used to it; and long-distance running is never as fast as short-distance. It can be invigorating - like a walk, only faster. Keep within an aerobic range, i.e. you can still carry on a conversation whilst jogging.
 

Monado: Thanks for the suggestion! Actually, since most of our walking is either to work or to local stores, we don't want to be all sweaty and out of breath by the time we get there. Tracking this walking encourages us to walk these short distances rather than drive them.

We figure it's better than nothing.