You don't have to walk outside...in case of bad weather, temperature is too hot, etc. All you need to do is to walk in place. My routine consists of walking 5 minutes every hour for the first week and then extending this to 2 more minutes until 10 minutes is reached.
You can walk more minutes but then you don't have too much time to do too much else!
I sometimes walk to Powwow music or rock and roll, etc. Occasionally classical!