If the weather ever improves, walking will become more attractive (though I did manage 16 city miles last Sunday). Walking is part of my stress reduction strategy, as well as burning calories and giving cardio-vascular exercise.
Coincidentally, there is now proof here that walking is as beneficial as running.
My own view is that walking benefits from the odd hill or two, but even pavement walking has an effect.
So your challenge for this weekend is to go for a walk, even in your local park or around the block, for an hour. Be fairly brisk, although this is not a sprint.
Your challenge for the week is to build walking into your routine. This may involve walking to get the Sunday papers rather than driving, or taking the stairs rather than the lift. You know your current routine.
Keep it up, and enjoy it!