Here's the scenario: Your day is nuts; you can't get to the gym (or if you can you can't spend much time there); you've got a meeting in two hours, a kid to get off to school, phone calls to return and a refrigerator to fill by dinnertime. You've got 30 minutes tops. What do you do?

1. Blow off your workout and feel bad about it

2. Blow off your workout and feel okay about it

3. Maximize the 30 minutes you have and feel great about it

If number three interests you, read on.

You'd be amazed at how often I've heard people tell me that they didn't bother to work out because they didn't have enough time to do their usual routine. I've even said it a few times myself. So out of necessity, I began thinking about the best way to use a short amount of time. And in the process, I discovered a few things. Here's the main thing I found: You can do a whole lot in 30 minutes. That goes for whether you're a complete beginner, in which case 30 minutes may actually seem like a lot, or an advanced exerciser. This week I'm going to give you an intermediate-to-advanced routine that you can do at the gym. In future weeks throughout the year, I'll give you other 30-minute routines that can be done at home, outside, with equipment, without equipment and for different fitness levels, including beginner and advanced.

Here's a good intermediate gym-based routine. Warm-up (2 minutes on treadmill) Treadmill: 8 minutes at best speed. If you're used to cruising at level 4, make this a level 5. If you're used to 6, go for 7. It's time-limited, so push yourself. Lat pull-down: 15 reps Incline press: 15 reps Lat pull-down: 15 reps Incline press: 15 reps Treadmill: 3 minutes; push yourself Dumbbell curls: 15 reps Dumbbell presses (over the head): 15 reps Dumbbell curls: 15 reps Dumbbell presses: 15 reps Treadmill: 3 minutes; push yourself Tricep press-down: 15 reps Lunges with light dumbbells: 15 reps (each leg) Tricep press-down: 15 reps Lunges with light dumbbells: 15 reps (each leg) Treadmill: 3 minutes, moderate to light intensity (cool down in last minute) Abdominal crunches: 2 sets of 20 reps Light stretching: 3-5 minutes You can make this harder in the obvious ways (faster on the treadmill, heavier weights during the sets), but I'm not sure you'll want to (it's pretty tough the way it is, especially if you don't rest between exercises). You can also make it easier by going slower on the treadmill, decreasing the weights and doing 10 reps per set. You can make it easier still (though still challenging) by not repeating each of the two-exercise sets that fall between the treadmill intervals, or, alternately, by changing the short treadmill runs to 2 or 2.5 minutes each. Your workout would be shorter but still pretty darn effective and efficient. Got a question or comment for Jonny? Post it on the Shape Up message board!