THE PURPOSE OF TRAINING IS TO CAUSE ADAPTATION(S); this is the first and constant concept to keep in mind in your first training session and every time you step into the gym after that. Success in any endeavor first requires a clear understanding of the Purpose and objective of the work. Once the Purpose is known, you can define the metrics (what you can measure and record) to determine success; this is the key to steady improvement.
If you are trainer you must methodically drive adaptation in each of the four pillars of fitness for every one of your clients. The Pillars of Fitness are Strength, Power, Explosiveness, and Endurance. You must define the metrics for each and create a methodical, progressive, and regulated plan to develop them. If your clients are Strong, Powerful, Explosive, and have Endurance, they can perform. You will have given them the fundamental physical tools to live a fulfilling life. If you are a client your (good) life literally depends on your trainer doing this, so if they are not planning (the actual numbers: intensities, sets, reps, etc.) ahead of time, and controlling it during training, fire them. Consistent adaptation requires progressive overload (of stress), and this doesn't happen accidentally.
It is essential to understand this concept because your mind must be clear and focused in the gym so that you can stay committed to your training program. You’re not training to entertain yourself or others. You’re not going to the gym because it’s trendy, and because people are “just supposed to go.” You’re also not there to show how tough you are to others or prove yourself to yourself.
All of these things might and probably will happen when you’re on a good training program, but they are not the primary Purpose of working out. If you follow a good training program and focus every session on driving adaptation(s), you will probably feel entertained and entertain others with your performance; you’ll undoubtedly look cool (trendy). You will look and feel tough (you really will be); in fact, the best way to prove yourself to yourself is to determine a purpose and have the discipline to stick with it. These are all positive side effects of following a rational training program with focus and dedication. These are consequences of a clear Purpose, but they are not the main point.
Far too often, people hit the gym without this fundamental concept in mind and end up wasting countless hours, days, weeks, months, and even years in confusion as to why they never seem to see the results they desire. Without a clear understanding that every single instant of effort in the gym (or any training area) is performed only to cause adaptation(s), the amount of effort will almost always be too little (this is the case when someone is in the gym just for entertainment or to be “trendy”), or too much (this is the case when someone is using exercise on a misguided personal trial).
Optimize Your Adaptations
To achieve our purpose (drive adaptation), the magnitude of the training load (stress) should be optimal; this can apply to a single training session, day, microcycle (a week), mesocycle (a month/group of weeks), periods, and year. Usually, most training units should have an optimal load, but you can do a workout/day/week/month in which the load is heavy (more than optimal), which we must balance with a unit of the same temporal size with a light (less than optimal) load. This way, the load is consistently averaged to the optimal over time. The way this is laid out in a training program will depend on your current training stage (Beginner, Intermediate, Advanced). This is why you must keep the concept in mind every time you hit the gym and when laying out or choosing a training program and also when reviewing and regulating it.
The key takeaway here is that anytime you hit the gym or even think seriously about working out, you must remember that the Purpose of training is to cause adaptation(s). This concept is crucial for clearing away any mental obstacles created by doubt in the gym and staying focused over the long haul, and this is the cornerstone of success.