Instead, when I get into these clutch situations, I just ramp back a little. I like to call them bookmark weeks. They're weeks when I'm not going to make any great strides, there just isn't time. So I spend a little less time, but make it quality time. I might not be able to run 45 minutes, so I run a little harder or on a tougher terrain for 30 minutes. I might not be able to perform a whole hour of weight training, so I spend a half hour doing less reps, but making sure to touch on all the usual body parts.
This isn't the ideal compromise for me. I really do miss being able to enjoy my workouts and getting lost in the zone. But, holding my place until responsibilities ease-up next week -- and I can get back to my full routine -- is worth it. Another huge pay-off is that I don't have to suffer through the "I just got back from vacation break-in period." That's the one where you go to work-out after so much time off you can't believe you used to run as far or lift as much weight as you could before you left.
If you're buried in responsibilities just remember: Something's Better Than Nothing.
