"You could draw an analogy to running, or some form of physical exercise," she said. "Maybe it makes you feel good because you are proud of yourself that you did it. You think that only a happy, energized person would be able to go for a five-mile run. Or maybe it's because it does something chemically to your brain, releasing endorphins or something like that, and that makes you feel good."
She says the research will continue, focusing on why it works, and whether it has a long-term effect.
It's possible it could have a clinical application, especially for people who can't get away from negative thoughts.
"It's hard to change what people think about," she said. But maybe changing the pace will help, at least a little.
For those who aren't clinically depressed, but need a little help during these troubling times, perhaps just engaging in a bit of mental gymnastics might help.
She suggests that people try to solve problems more quickly, like reading at a faster pace, or completing a puzzle in quick-time.
It's not likely to stabilize a manic-depressive. But maybe it's worth a try.