While the gym offers the best choices of free weights and weight machines for an intense bodybuilding workout, it's not always an available option for everyone. Trips away from home, limited time and money, and long commuting distances are among the reasons that a commercial gym may not be available to you. Nevertheless, there are almost always ways to get the workout you need if you use your imagination.

As someone who travels around a lot, I've personally had to find a lot of creative ways to stay in shape. I often don't have access to weight machines, or even free weights in many cases. I've found ways to make due with what's available in hotel rooms and city parks, and plenty of new ways to add more resistance in my exercises.

While you're performing the exercises I'm about to go over, keep in mind that all the same rules apply as they would if you were at the gym. Warm up just as you would at the gym, drink plenty of water, and don't skip out on stretching. You'll need to work your muscles at full capacity with high resistance exercises to see the best results. This can be a bit more of a challenge if you're used to using specific weighs and resistance settings that you can easily find at the gym, but there are still plenty of other ways to go about it.

When I haven't had a barbell available, this is what I've often done to add extra resistance to my exercises: As a traveler, I always have my big trekking backpack with me wherever I go. Backpacks, even smaller ones, are super easy to load up with extra weight, and can be used to increase resistance on a whole bunch of different exercises. For leg exercises, I lift it up and set it on top of my head. I mostly just use my hands to stabilize it. Usually, I fill it up with books or containers full of liquid.

Books and heavy containers can also be a great substitute for a dumbbell. I often slip a water bottle into a long sock and tie two together for a weight that I can sling behind my neck or over my shoulders. Purchasing weight vests and weight belts is yet another option to add resistance to your workouts.

To get an idea of how many pounds I'm adding with these makeshift weights, I usually use a bathroom scale, if available. First I weigh myself without the weight. Then I step on the scale holding the weight, and I simply subtract my body weight. The difference is what I'm adding for resistance.

Now we'll go over some of the best bodybuilding exercises you can easily do without going to the gym.

• Exercises for the legs

Squats

Squats exercise the glutes and thighs, and should be done with the feet about shoulder-width apart, with the back as vertical and straight as possible. Lower yourself down slowly to a squatting position, then raise yourself back up to complete a repetition.

Lunges

Using your own body weight can work just fine with lunges, or you can add resistance as I talked about above.

Position yourself with one foot in front of the other. There should be about two feet of space between your front and back foot. Keeping your upper body vertical, bend your knee on the leg you have out in front. Lower yourself down to the point where you feel comfortable, then raise yourself back up to the starting position. Switch up your legs to do a full set of repetitions on each one.

• Exercises for the back

Pull-ups

I've found pull-ups to be one of the best exercises you can to for the upper body. In situations when I had no access to a gym, they've given me great results in my deltoids, biceps, lats and even my abs.

When doing pull-ups, always let your muscles do the work, and avoid swinging motions that can boost you up with your body weight. Depending on the muscles you want to focus on, you can make your own choice as to how far you drop. I prefer to drop all the way down to let my muscles work in their full range of motion.

Any horizontal bar where you can hang without touching the ground can do the trick. You can almost always find something in the park, like monkey bars or even a swing set. Portable pull-up bars that you can easily fit into a door frame are also a very handy option.

Bent-over row

For the bent over row, find something sturdy that you can use as a substitute for a bench. I find that a bed works well, or even two chairs sitting side by side. Crouch down with your left knee and elbow braced on your bench, and stand on the floor with your right foot. With your right hand, grab your weight.

Pull the weight up to the right side of your chest, staying in a bent-over position with your back in a straight line. Return the weight down to its starting position by extending your arm straight down as far as it will go. Switch over and sit your right arm and leg down on the bench when you’re ready to work your left side.

• Exercises for the chest

Push-ups

Push-ups build arm, chest and shoulder strength. Do them by lying on the floor face down and pushing yourself up with your arms while keeping you back straight. Push-ups are great because they're a very simple exercise that you can do with your own body weight, and they're also very versatile. Spreading the hands further apart will make the chest muscles work harder. Setting them at shoulder-width makes for a good balance between working the chest and arms.

You can add resistance by wearing a backpack, or by simply elevating your feet. You can set your feet on an elevated surface as you push up, such as a chair or a bed. I especially like stairs, because they give you several different difficulty levels to choose from.

Dips

Dips are similar to push up as far as the muscle groups they work, but different in how they're executed. You'll want to find a way to suspend yourself by holding yourself up with your arms. This can honestly be a challenge sometimes. Two very sturdy chairs can do the job, but I tend to prefer something a bit more stable. I've managed by setting a table in back of a couch that was the same height, leaving about a foot and a half of space in between for my body to hang.

Once you've found a safe setup start by letting yourself hang with your arms straight, supporting all your weight. Slowly lower yourself down until your forearms are sitting flat, then push back up with your arms so that they become straight again. Try to keep your body straight up and down and avoid swinging.

So even though the gym offers the best solutions with free weights and weight machines, you should now have some good ideas of how you can still get good muscle-building workouts even when a gym is not an easy option. By using a bit of creativity, you'll still have plenty of options available for getting a great workout.