First, check to see what facilities your hotel does offer. You may be pleasantly surprised. Most hotel websites list their facilities, so you might even make the availability of exercise equipment one of your criteria when deciding where to stay.

Also, some hotels have associations with local health clubs, and some clubs will let you pay for a day's use.

Now let's assume the worst - no equipment, no pool, nothing. Not only that, but you're schedule is packed.

You answer is body weight exercise done in a circuit. These can be incredibly challenging when done with some of the variations I'll describe. And you can do an effective workout in 10 to 20 minutes without leaving your room.

First, warm up by stretching and doing slow, controlled repetitions of the calisthenics.

Then do the work out proper.

The simple version is to do circuits of deep knee bends (squats), push ups and sit ups.

You obtain variety and progress by changing the number of exercises per circuit.

For example, beginners might do five repetitions of each exercise and rest between exercises and each circuit. More experienced may increase the repetitions and decrease the rest time.

Also, you may want to perform a different number of repetitions for different exercises.

For example, you might do 8 push-ups and sit ups per round but 15 squats.

One way to increase the intensity as well as tract your progress is to pick an exercise circuit, for examples 10 push ups and 15 squats, then see how many times you can complete that circuit in a set amount of time.

Depending on your fitness level, that time could be from 5 to 20 minutes.

Obviously, you can vary the exercises.

A "tabata" protocol is a very intense, effective approach to exercise. This approach is named after a Japanese researcher who proved the superiority of short intense interval training over long slow training in increasing both anaerobic and aerobic fitness. When I describe it, it may not sound like much. Give it a try before you discount its effectiveness.

A tabata routine involves warming up thoroughly, then doing a given exercise full out for 20 seconds, resting 10 seconds and repeating that interval eight times for a total of four minutes of exercise.

The original study was done with the athletes on an exercise bike, but it can be used with any exercise you chose.

Again, it may not sound like much reading about, but give it a try. The key is full-out intensity during the 20 second exercise period. By the end of the four minutes, those will be the longest 20 seconds you've ever experienced.

For the travel workout, you could "tabata" four minutes of push-ups, four minutes of sit-ups and four minutes of squats. This gives you a resistance workout that simultaneously maintains your aerobic fitness.

Challenging body weight exercises you can do are spiderman push-ups (bring your right knee to your right elbow as you lower yourself, then left knee to left elbow on the next rep) and squat-thrusts (squat and at the bottom, put your hands on the ground and thrust your legs out behind you. Bring you feet back to the squat position and stand up).

An advanced modification of the squat thrust is to do a push-up or two in the bottom position and to leap up from the bottom of the squat, actually jumping in the air.

All of this can be done without any equipment at all and without leaving your hotel room.

If you want to bring a little exercise equipment, I recommend a jump rope. It's light and compact and adds variety to your work out.

With a portable chin up bar, you can work your back and biceps - the only elements missing in the routines above.

But even with out equipment, it is possible to return home fitter than when you left.