I mentioned, a while ago, using the fitness app Quick 4 to get myself doing exercise on closer to a daily basis. It has certainly helped my metabolism, although I can't really tell how much more than that it's done.
I haven't really lose weight (maybe a few pounds) in the intervening weeks, though it's possible body fat has gone down (I tend not to lose weight when exercising heavily, just to get more muscular. Dunno if that's a personal weirdness, or a symptom of how I exercise, or something else).
But since it only lasts four minutes, I have done some thinking (and experimenting) with how to make it more effective (burning more calories, at least). There are eight exercises, so here are my thoughts on each of them:
Running in place: lift knees up higher and swing arms more
Jumping jacks: keep arms straighter and spread legs wider
Push-ups: keep back, all the way from feet to head, straight; never rest weight on ground
Jumping squats: go all the way into a crouch, don't pause, go as close as possible to straight up
Bicycle crunch: be sure to pull with abs, not shoulders; have arms hit as far above knees as possible
Burpees: actually got nothing for this one
Mason twist: keep feet off ground, but move knees as far as possible; keep hands next to torso
Mountain climbers: arms and back straight, back parallel to ground, keep shoulders behind hands
All of them, of course, also increase impact by doing them faster.
I've also increased it by sometimes doing the Quick7 workout as well (a couple hours later).