Starting the week off walking for just 20-30 minutes the first day helps me get the motivation to continue to work out the rest of the week. I do my cardio 4-5 days a week all in consecutive days. So say I start on Tuesday, I will walk for about a half hour on my treadmill, alternating faster and slower paces and inclines. Wednesday and Thursday increase my times. By Friday I'm walking for an hour or longer and including some light jogging. Saturday, Sunday and Monday are rest days.
You don't need a treadmill you can do this outside as well. I have small children so being inside on a treadmill is easier to care for my family while I exercise.