Hi there
When it rains I turn on the computer, go to YouTube and find Leslie Sansone's Walking Videos ... you will find anything for a 2 min walk right up to a Brisk 5 mile walk ... she is brilliant, they are fun and easy to do.
I don't know your fitness level but here's the 2 min one to get you started ... http://www.youtube.com/watch?v=Xd6wuZEXuIc
Best Regards
Hazel