I had back surgery shortly before I started making changes and so I was very limited on what exercises I could do. However, I did exercise every day (5-6 times a week).
I started by walking. I could only walk about 1.5 miles an hour and could only go for about 10 minutes. I just kept adding to that and speeding up as I was able to. When I was given clearance from the doctor to add additional exercise I did so. It started with the pool and doing basic exercises in the pool, and moved on to some light weight lifting. I continued walking and lifting for several months.
When I was cleared to do yoga, pilates, and aerobics I started adding in videos. I did yoga and pilates, cardio barre, and continued walking.
After a couple more months I was able to add higher impact aerobics in. My favorite is zumba.
I recommend finding something that you love to do and makes the time go by fast.
It doesn't matter what kind of exercises you're doing as long as you're consistent and work hard.
I exercise 5-6 times a week for about an hour a day.
I firmly believe in combining aerobic and weight lifting for the best results.
Transformation.com is an excellent website with weight lifting and aerobic program recommendations.