Here's an idea for you...
Sunday - hour walk
Monday - 30 min simple strength training (push ups, sit ups, tri-dips, squats and lunges)
Tuesday - 15 minutes jumping rope & 50 jumping jacks OR a 30 minute cardio exercise video/DVD (available at the library if you don't want to purchase)
Thursday - 30 min simple strength training (push ups, sit ups, tri-dips, squats and lunges)
Friday - 30 minute walk
Saturday - day off
As always, you should consult your doctor before starting any exercise program. There are many AWESOME fitness videos/DVDs on the market to keep your workouts fresh. My favorite cardio workout is a nice, long walk/run outdoors.