Around January 10 this year, I strained my neck and stopped lifting weights to let it heal and avoid injuring it further. Although it was completely healed after three weeks, I didn't do any resistance training for two months (and I stopped doing cardio workouts over a year ago). It was pure laziness. (As for the cardio, I decided last year it was just a waste of valuable dance time.)
How did this affect my health and fitness? At January 10, my weight was 118 pounds. Today, March 7, it was...118 pounds. My pants (all tailored, no elastic waists) fit just as they did in January. No, I'm not the type who can eat anything without gaining weight: last year at this time, I was in the middle of losing 20 pounds, going from a high-carb, low-fat diet to a low-carb, high-fat diet.
This bears out the research I've done on health and fitness: between diet and exercise, your weight and health are influenced 95% by diet and 5% by exercise. And unless you're going to extremes, calories don't matter.
That isn't to say exercise isn't worthwhile. My workout tonight (to the Ballet Conditioning DVD) was harder than I remembered it, got me out of the funk I'd been in for a few days, and it physically felt great.