wb416
Contributor
I used to weigh 250 pounds and got down to 185 with biking. I now weigh ~165 through a combo of biking and Wii Fit. I was biking to school then to work after graduating; commuting via bike puts the daily exercise into your schedule and thus you're very highly likely to stick with it. Stay off the roads whenever possible - go on bike paths, dedicated trails, etc. Some drivers aren't very good at avoiding accidents, and 1/5 is under the influence of something.
You will require winter biking gear. A good jacket will make all the difference in the world. Wait. What kind of winters do you get in Florida?
One thing you will hear - which is false - is that biking is low-impact. It is not. It is just as likely to damage your knees as running, and I know several cyclists who have required knee surgery. (I am not one of them.) Go easy on your knees by ensuring that your legs are warm in the winter. Your legs will not feel the cold as easily as your chest. In other words, if you can't wear just a tshirt on top, you can't wear just shorts on the bottom.
Kudos to you for commuting to work. Not possible with my job, but sometimes I wish I had a job that I could.
Spinning at a higher rate (in easier gears) can help the knees too... and keep the heart rate up nicely!