It is always possible to do "something". I think defining "exercise" too legalistically, that you have to work out at a gym for 30+ minutes, etc., is what gets in our way.

http://psychcentral.com/news/2010/04...ion/12627.html

It's hard to get out of bed but not impossible. It's a choice and you can choose to do the hard stuff (get up and shower, dress, go eat a healthy meal) or stay in bed and sleep. There's an armed forces slogan I like, "The difficult we do immediately, the impossible takes a while longer."