I know many people who complain that they go to the gym 3 times a week, every week and they aren't seeing results. What I notice when talking to them is that most people do the exact same thing every time they go to the gym. The fact of the matter is the human body is very good at adaptation and efficiency. The bottom line is the longer you do the same exercises or activities the less of a "challenge" it is, therefore the less benefit you get from it.
Let's look at cardio for a moment. If you run 3 miles 3 days a week, without any variation, after your body goes through its initial adaptation, it really doesn't need to change anymore. And to top that off, since your body is now "good" at running 3 miles, the heart rate doesn't elevate as high and your calorie burn goes down. So you are getting much less benefit from the same exercise because your body has now adapted.
The result is the same with resistance training. If you do the same exercises and the same weights, your body adapts and you get less benefit. With lifting, you break down muscle and it rebuilds tighter and stronger. You do this by pushing to a level you can't do. For example, your 10th rep of a 10 rep set is a struggle, your body has to change to handle that load. If you can easily perform a 10th rep of a 10 rep set, your body has no need to change so it doesn't. Like cardio, your body adapts to a lifting protocol and if you don't mix things up you will plateau.
So what do you have to do to keep your body from becoming used to your workouts? You have to have variation and intensity.
Variation is simple. It means always changing up aspects of your workout. You can do this by exercise selection, amount of reps, amount of sets, varying your rest between exercises, and changing the loads you are lifting.
Intensity is how hard you do what you are doing. You can simply "go through the motions" or you can push through harder and faster. While the former will yield little results the latter produces the greatest body change!
The best way to insure that you have variation is to write stuff down! I have always been a pretty fit person, but recently I hit a major plateau. I started writing stuff down. Now I make sure that I change up the exercises every 4 weeks and I am constantly changing the weight. I have since broken through the plateau and am seeing some good results. Simply seeing it on a piece of paper keeps you conscious and holds you accountable. As far as intensity goes, that is all on you! At the end of a set you should feel like you worked. If you finish an exercise and could have done a few more reps then the intensity is probably not high enough. The good thing about variation is that usually forces you to keep the intensity up because there is always something different forcing you to do something you are not used to thus making you work harder.
So basically, your body will change if it has to. If you are doing the same old thing all the time your body has no reason to change, but it you are continually changing workout variables and pushing your intensity the body MUST change to accommodate the demand! So work different and work hard and you will reach all of your fitness goals!
