Of course you can do that. Many people do just that. They go to the gym day after day and do the exercises they feel like doing on that day, using the weights they feel that they are capable of lifting at the present moment. It’s fine, nothing wrong about it.
When you do any type of physical activity that is unplanned and that follows no direction, it is called exercising. Exercising is great. It helps you build some muscle; it expands calories and might help you lose weight; it is great to ease your mind and it brings about a ton of health benefits.
However, what I just described is not training. Training implies following a plan. A plan that was created to achieve a specific goal. Training means following a series of well-defined steps that will progressively take you to where it is that you want to go. Following a program is training. Going to the gym with no program is exercising.
I am not an advocate of one more than another. But understand that you cannot feel sorry for yourself from lack of progress if you don’t follow a program. It would be like trying to get to San Francisco from Boston with no map or directions. Odds are quite high that you’ll end up some place else.
Muscle building is an adaptative response from the body. It is the body’s answer to a task that was really hard. A way for it to be ready next time it faces that challenge. You lift a weight that is really challenging, and the body respond by adding tissue to the muscle that has done the work. It is a simple way to put it, but you get the gist of it. The key here is to challenge the muscle enough to force it to adapt. To force the creation of new tissue.
The human body is a fantastic adaptation machine. That is why humans can live in very cold areas and very warm areas as well. That is why hard manual labour can turn a very weak individual into a tough, hard working person within a few months. But the body will adapt when the stimulus is high enough.
When you lift weights, you must force the body into creating new muscle tissue by increasing the stimulus constantly. This is especially true with beginners. If you exercise, odds are that you will lift the same weights workout after workout. You use no plan when you exercise. You don’t keep track of the weights that you use. Please keep in mind that humans are creatures of habit and comfort. Thus, you are very likely to become very comfortable at a certain degree of discomfort and stop trying to challenge yourself at a set point. In simple terms, you’ll do the same workout over and over again, with the same weights, same reps, same tempo, etc. And you will cease to progress. Why would you? You do not expose the body enough to a stressor (heavier weight) to force it to adapt.
Training, or following a program, does the exact opposite of that. A program is a plan that is designed to progressively, over a certain period of time, challenge more and more the body into growing. It gives you the exact steps to follow to prevent staleness and it help you keeping track of your progress. It is the shortest road to success. It removes the guessing game out of the picture. It is your blueprint to build your house, metaphorically speaking.
You need to get stronger to grow, especially in your first lifting years (no matter what your actual age is). Let me give you an example of what that means in real life. You start training and on a lift, say a flat dumbbell press, and you use 25lbs for 12 reps. That is the maximal amount of weight you can lift as of now. You train according to a well-designed plan and strive on adding 1 more rep, or 5 lbs every time you hit the gym, for weeks and months on end. You write down your scores in your logbook and follow your plan and, after a year, you are now able to press 50lbs dumbbells for 12 repetitions. You have gotten much stronger and as such, you’ll have bigger pec muscles. It cannot be any other way. If you had followed no plan or specific course of action and went by feeling or habit every time you trained that year, do you think that you would be able to press the 50’s? Probably not. In fact, most gym goers use the same weight day in and day out and make little if any progress.
A weight training program must be tailored to your level because nobody is at the same place when it comes to lifting weights. Beginner and advanced lifters have very different needs in terms of reps, sets, rest, frequency, recovery, use of advanced techniques, etc. Therefore, the plan that you use today, as a beginner, will be of little use to you in 2 years from now. And that’s perfectly fine. It just means that you are progressing, and that your body needs a different stimulus than the one it needed before.
We are goal-striving creatures. Most of us function optimally when we are chasing a goal. Think about it for a second. If you want an employee to perform above expectations, give him the opportunity to get a promotion and to advance in the company if his work is done well. The salesman works on commission. More sales equals more money. Both the employee working to get a promotion and the salesman will deploy many efforts to reach their goal. It is their very reason to put in extra efforts, to strive to get better. A training program helps you progress faster using the same principle of setting a goal. In a good beginner’s program, you should aim at beating your previous score by a few pounds or more reps, each and every week. Exercising to ‘be healthy’ does not give you the same drive and passion. Only planned training to reach a specific goal will do that.
Whatever your profile and goal is, if you feel that your progress is disappointing and if you’re looking for that extra ‘oomph’ to fire you up and start gaining muscle at a faster rate, consider following a good, well-designed plan for a year and see what happens to your results and your attitude in the gym.