Q: how important is stretching in this whole scheme of things? How long do you suggest we spend on stretching?

A: Stretching/warm-ups both before and after exercising are not a matter of life and death, but they are a good idea to prevent injury, reduce muscle soreness and improve flexibility. My recommended stretching routine for cardio is simply a 2-3 minute walk or light jog both before and after the exercise.

For weight training, I recommend the same 2-3 minute walk, followed by muscle-specific stretching (don't bounce, hold the stretch for 5-10 seconds, then slowly release. Repeat 2-3 times), followed by exercise-specific warm-up: 1 set of 4-6 reps using weight that's around 50% of the weight you'll be using for the main set. So if you plan to do bicep curls with 80 pounds, you may precede it by doing a set of 6 reps using 40-45 pounds. After the exercise I recommend you repeat the muscle-specific stretch and you can optionally end your workout with the 2-3 minute light walk. Total time spent stretching/warming up/cooling down will usually be 10 minutes or less per session.

There are certain exercises and muscles for which stretching becomes more important: calves, quadriceps (front thigh) and lower back can all get REALLY sore after intense workouts which could literally leave you debilitated for a day or three. So good stretching before and after exercises is especially important for calf raises, squats, lunges, and deadlifts.

It's also a good idea to do some light stretching on non-exercise days -- this tends to lessen muscle soreness and gives you a little extra flexibility training. On the whole remember that stretching is just preparing for your main routine, so don't go past the point of discomfort while stretching, don't bounce, and don't work yourself to sweat just stretching and warming up.