ding ding ding.. we have a winnerDo not EVER go on a diet. Change your lifestyle instead.
like anything -brisk is in the eye of the brisker...If you are big like I was - do not believe people that tell you that you have to walk briskly for it to be of benefit. I couldnt do anything briskly back then. Any walking is of major benefit.
Don't obsess over the scale, judge your weightloss by how your clothes fit.