I’ve gone through my entire adult life so far in one of two conditions where physical exercise is concerned:  I’m either in a “groove,” or a “rut.”  A “groove” is a period of time where I’m exercising regularly, and generally feel “fit.”  Conversely, a “rut” is a period of time where I’m slacking off, skipping workouts, etc., and just generally feel “unfit.”  When I first started commuting by bike on a serious, regular basis, I entered an extended “groove” period.  I spent most of 2008 and 2009 in one big, happy exercise groove.  Now, it’s 2010, and for some reason, in spite of still biking 80-odd miles per week, I feel like I’m in a “rut.”  I didn’t think this would be possible.  Maybe I’ve gotten to the point where bike commuting has become so ingrained in my psyche, that I no longer consider it a form of exercise.  Or more likely, it could also be that I’ve reached a fitness “plateau,” and my overall fitness is no longer increasing as a result of my riding, so I feel like I should be doing more.  Not quite sure what to make of this, but I do think I need to re-introduce some cross-training, such as weight training and jogging, back into my regular routine.  The issue with those, of course, is finding the time and motivation.  The beauty of bike commuting is how well it dovetails with my daily schedule.  Everything else needs to be “fit in” somehow, which makes it less likely that I’ll keep it up.  Hopefully at some point I’ll figure it all out.