What is convenient, available, useful, and efficient is often what works the best.

The Amazon Alexa bot by your bedside works best for waking you up in the morning. A phone is much more useful for getting directions to a bakery across town than a dedicated GPS device. Once people finally buy a laptop they really love, they rarely go back to a desktop in the office.

You might disagree with some of these statements, but I've found that those four words above (convenient, available, useful, and efficient) are incredibly important when it comes to developing new habits. And, incidentally, they are important to keep in mind if you are trying to break a bad habit--like scanning for news on your iPad before bed.

With exercise, you might already know it's important in terms of healthy living and even helping you live longer. There are countless studies about that. Yet, what might finally make you use the machines on a routine basis is is when those four words come into play.

Convenient: The machines should be located near an area where you work or relax often
Available: You should be free to use them at will, at any time of the day
Useful: The machines need to actually work and do their job as advertised
Efficient: Each one should work thoroughly and within a set time period, no wasted effort

I decided to test this theory recently. I tried out three different exercise machines, each one sitting right next to my desk, to find out if I used them more. Skipping ahead right to the final results, I worked out so much and so often, and tested so many of the features, that I lost 10 pounds in a month. (I also did some intermittent fasting.) My biggest finding is that the four words above are incredibly important.

I started by testing a rowing machine called the NordicTrack RW900 Rower, which costs $1,599. With a 22-inch screen mounted in front of me, I was able to take multiple classes in a studio and also watch an actual rower on a river (many of them took place near London and in Africa). The idea is that you forget you are even exercising as you watch someone on the screen. Each session also adjusts the tension of the row machine on the fly. For me, it worked. I spent a good 30 minutes on the machine every morning. My only slight issue is that I wanted a little more variety in the workouts and the real-world locations.

Next, I spent about 15-20 minutes each morning on the new Peloton Tread, which is an absolutely joy to use. The base machine without extra weights or mats costs $4,295. Like the row machine, the Tread features classes that show you how to use the machine and motivate you to keep running or walking. There are live classes and recorded routes, including one on a mountain in Colorado. Adjusting the tension is easy because the knob is located to your right. You can also raise and lower the tilt, which helps you get a more robust workout. Someday, I'd like to test a treadmill that lets me play a video game or watch a movie, but I do like the interactive classes. Plus, I never slipped.

Lastly, I "cooled down" from rowing and running by biking on the CAR.O.L. Fitness Technologies stationary bike, which costs $2,995. Now, I'm an avid cyclist so I was partial to this machine and loved how it all worked. The idea is to do short workouts that change the tension as you cycle from easy to very difficult all in the same workout. Based on scientific studies, the shorter workout of about 40 seconds equates to a much longer workout, per company assertions. I can see how that would work, because I did experience a tough workout in a short period of time and the bike helped me get ready for spring biking season. Whether it would work over several months is unknown.

Overall, these three machines helped me lose about ten pounds in only a month (the length of time I was allowed to borrow them). The main reason is that they were right next to me in my office, a constant reminder to climb on board and do a workout.

My theory with all workouts is that you have to remove any barriers to success. Put the machines right next to where you wake up or where you work. Change into workout clothes right away in the morning. Skip going to the gym if it means having to spend that extra time driving across town. Choose a machine that matches your own lifestyle and tastes.

I'm a fan of all three machines--they worked as advertised and fit my daily routine.