**I am just telling you what worked for me.  You should always consult your
medical provider before embarking on any new physical activity.

I have found that walking is really one of the best exercises to start out with.  
Our bodies are amazing machines and will adapt to walking but you can use
it quite effectively for at least 1 year.  You will have to modify it as far as
distance, time, and speed in that year but it is a effective and cheap mode of
activity.  

The first time I actively walked with any sort of plan was the period I lost the
185 pounds in 1990.  I was back in college and did not have a lot of money
to spend on extra things other than paying rent and utilities.  I lived in
Brookings, SD at the time which is very nice from June until October, but
November through May is quite cool.  I would walk routes down the city
streets using a stopwatch I bought for a relatively little amount.  I set it for 15
minutes at first and I would walk down the street for 15 minutes until it
beeped and then turn around and walk home.  I added time on slowly but
surely and got up to the point where I was walking for 80 minutes.  I did this
pretty much every evening.  I did this from August until late October and had
lost enough weight that I could wear my largest pants over a pair of sweats.  
I used a separate sweatshirt and hooded sweat jacket for exercise and with
the layers of clothing went ahead and walked in most weather.  I walked
through some pretty heavy snows even and it was really quite peaceful. I
used walking as my only exercise this end of the yo-yo.

The next time I lost weight was when I lived in Carlsbad, NM.  I resorted back
to my walking plan and used the same technique of building up to a 5 mile
walk each evening.  The nice thing about Carlsbad is that it sits on the
Pecos River and there is a paved path around a large portion of the river in
the middle of town.  It was nice not to have to fight with traffic and streets for
a change.  I walked this path until I had lost 125 pounds which was after
about 10 months and then I joined a gym.  I luckily had relatively few
expenses and decent income at the time. The gym was cheap and I was able
to hire a personal trainer who also charged much less than what was normal
even at that time.  I lifted weights 3 nights a week for an hour and then did
cardio in the evenings between.  I ended up before I moved having to do
cardio pretty much each morning also for an hour to maintain my loss. It
really kind of sucks how efficient of a machine our bodies are, but what do
you do?  I was following the very low fat and higher carb plan and was
hungry often so that didn't help.

This time around, I started in Phoenix where I joined the gym.  At the gym I
would either ride the recumbent bike or walk on the treadmill.  I found that for
some reason I just do not really enjoy lifting weights alone.  I tried lifting and
finally just went back to the walking/cycling as I felt comfortable doing that for
some reason.   I moved to Albuquerque a year ago and joined a gym fairly
soon after getting here.  I continued with the recumbent bike and treadmill
working my way up to 80 minutes.  It is not as easy to do the long hauls at
the gym as they generally have people waiting to do their own cardio and
limit you to 30 minutes unless you just sneak by.   Albuquerque has a lot of
nice trails all through the city and in the spring, once the weather got nicer, I
started walking on the trails.  In the summer I also purchased a mountain
bike and started riding it on alternate days of walking.  There are nice dirt
mountain trails here and on the weekends I would go hiking on them for a
couple of hours to kind of 'shake it up.'   Now that it has been cooler again I
have returned to the gym.  I had built up to walking from 9-11 miles a day on
the trails and could not do that sort of time on the treadmill so I have recently
started to run.   My hopes are to be able to run for 1/2 hour or so and burn
the same amount of calories as the walking but we will see what happens.
Exercise and other activity.