Substitute for walking on rainy days

Normally I go for a walk everyday for about 30-40 minutes. Today it's raining and the forecast says it will rain and rain and rain and rain throughout this week. :(

Of course there will be some dry periods, but I don't want to be caught by the rain in the middle of my walk, well I will stay home. :)

What can I do at home to substitue my walking? It shouldn't be anything fancy because I'm on my second week of blend, so I really got my workout already done. Yoga doesn't count too, because that's my go to bed routine. :)

Help. :) :)