A lunchtime stroll is good too, but part of the point here is that the timing of the light is important with respect to circadian rhythm. As a northern latitude dweller, I leave the house in darkness and return in darkness. Bright light in the morning with my coffee kickstarts that circadian pattern at a time that I couldn't otherwise get light in winter months.
Hibernation during winter might be natural in some sense, but it doesn't fit well with modern living. I'm outside about as much as one can and still do computer-oriented work. I also, rain or shine, put in 50-100 miles per week on my bicycle in commuting / errands, which means that I get a decent baseline of exercise. But, that still doesn't cut it. It's light therapy or relocation for me.