Add 1 to 2 minutes to your walk each week until you can walk for 30 to 40 minutes.
Progress to walking 4 to 5 days per week.
Start with 3 to 4 strength training exercises with a weight that you can easily lift 10 to 15 times.
Add 2 to 3 strength training exercises each week until you are able to do a full resistance training routine of 10 to 12 exercises.
Increase the weight or resistance slowly to the point that the 15th repetition is difficult but manageable.
After exercising regularly for a month or two add a 2nd set to your resistance training routine.