Weight Watchers is a good, sound approach to losing weight. I averaged about 1.5 to 1.7 pounds a week on it. That is slower than what you want to do in eight weeks. But, doing it too fast is not good, either. Weight Watchers aims to feed you enough that your metabolism does not go into starvation mode, but you lose weight, too.
I had a hernia pushing through the stomach muscles in the 1 o'clock position from my navel. You have an organ called the omentum that migrates inside your stomach wall. Sometimes it covers the hole for you. Sometimes it is elsewhere, and that is when you get the painful bulging. I have a clerical job, but I have loaded truck trailers, too. I would not want to try it with a hernia.
I also was not riding regularly nine years ago when I had my surgery. I did hear too many stories of guys who thought they were tough and did not follow the doctor's guidelines on what was allowed. Those guys usually blew out their surgery and had to have it all done over again. I remember being limited to lifting nothing heavier than four pounds for about six weeks. I had an abdominal incision six inches long with a nylon patch inside seven by ten inches, too. An abdominal incision takes the starch out of you more than you would think.
You might be capable of riding a bike after a couple of weeks; but should you crash, your incision could be subjected to some severe stresses.