"No Pain, No Gain" Follow-Up

Thinking more about the previous post, which noted the mounting evidence that merely grinding out aerobic exercise may not help much,. Painful all-out sprinting, even for a few short minutes, brings far greater weight loss and cardiovascular benefits than long stoic sessions of merely heighteened heart rate (if you haven't read the post yet, you may want to take a look, below, before continuing here)...

I'm wondering how much of the effect is psychological. You may have heard of the mega-bizarre recent study where hotel maids were simply informed that their daily work routine was fairly strenuous...and subsequently lost weight and reduced blood pressure, apparently via the psychological shift alone, without any actual changes to their activities (here's an article with more info).

Could it be that it's not the sprinting itself that causes the benefit, along with a side effect of pain and fatigue....but the pain and fatigue themselves directly cause the benefit? There's no better way, after all, to psychologically hammer home to yourself the realization that you've really exerted yourself than panting uncontrollably and suffering stabbing pains to the sides.

I wonder if there's some way to create an experiment where subjects performing their normal exercise routine are caused to simply feel as if they're exerting themselves much more...