Does this apply to pacemakers??
In all seriousness, I do agree with the idea - a fair few too many people I know are living an overly sedentary lifestyle, and when the suggestion of doing something outdoors is aired to them, you can see the disgust in their face at the very notion of stepping outdoors and in amongst that green stuff that comes out of the ground. I live with one person who's addicted to TV, and one of my best mates is addicted to Guild Wars.
I used to be the same; I could once be found spending from dusk til dawn playing Heroes of Might and Magic, and eventually, raiding in World of Warcraft. I admit - I got completely addicted to it, and it was only when confronted by my missus with a pretty stern ultimatum did I give it up. Cold turkey is hard but fast, and it was only about 2/3 days after I gave it up that I realised that there's a whole world out there to see and experience.
So, er... yea! Go outside! Go sniff trees, pat dogs, climb hills, jump streams and be chased by bulls. It's better that going pale through lack of sunlight!