Even though I'm huge, I won't let that get in my way. Walking was wasting my time. I wait til it's dark, put on running sneakers and head outside to jog. No, I can't go all that fast or far (yet), but it doesn't matter. I go until I am totally out of breath, face beat red and sweating! The metabolism boost was pretty much instantaneous. Try it! You'll see what I mean & it's also an instand mood-lifter!
Try and get a good pair of running shoes - it's worth the small investment.