I am 82 years old. how long should it take me to walk a mile to exercise my heart at proper rate and lose weight? right now it takes me 23 minutes to walk a mile. that works out to 2.6 mph.

It's : It's hard to answer this question without knowing more about your overall health. The fact that you can do this walk without apparent pain (at least, you didn't mention any) indicates that your peripheral arterial system is in pretty good shape, but i don't know anything about your heart or lungs. Nor have you indicated how much weight you need or want to lose. In general, when we're looking at exercise levels, we look at the patient's heart rate and age. The maximal heart rate recommended during exercise for an 82 year-old is 138 beats per minute. The target level would be somewhere between 70 and 110 beats per minute, and ideally you would hold that rate for about 20 minutes to get any aerobic benefit. There are devices that can give you a continuous readout of your heart rate. I would recommend that you get one of these devices and check your heart rate during your current workout. That will let you know if you're on the right track. Before increasing the level of exercise, you should check with your doctor.

Not too bad...: That's a leisurely pace, which would be fine for someone at your age, no offense. Studies have shown that such a pace can cut all cause mortality in octagenarians in half, so it's quite effective.