Have you ever wondered why so many people have vision problems? When you look at how many people are essentially blind without prescription glasses, it makes you think that something is very amiss with our environment. There's no way that humans in ancient times could survive with the crappy vision that they now have.This got me worried when I was thinking about it in conjunction with doomsday predictions, so I looked it up.
The scientific consensus seems to be that nearsightedness is caused by too much close work, in other words reading and computer screen use. Another suspected cause was lack of outdoor play.
So hopefully this may provide you guys some impetus to get outside and do physical activity. Bad vision is a very noticeable negative effect of sedentary lifestyle, at least if you wear glasses. So it can serve as a constant reminder of the need for physical activity.
Do you guys feel greatly less depressed when you have run or ridden a bike outside? When I do something like that my body just seems to get 50% better. I even seem to get stronger erections. It only lasts a day though. You have to do it continually.