This appears counterintuitive; people typically predict intense states to last longer. The hypothesized for this disconnect is that, intense states trigger psychological defense processes that reduce the distress, while less intense states do not trigger the same psychological defense processes and, therefore, less effective attenuation of the stress occurs.
They’re using walking (region alpha) vs biking (region beta) region as an analogy: “paradoxically” you’ll reach some further distances earlier, based on your choice of mode of transport. Which wouldn’t work in my case cause I’ll take the bike to the grocery store down the street. At any rate, your “choice” of defense mechanism influences your rate of recovery, is what they’re trying to say