
The key to customizing a plan is understanding the structure of P90X, because any program should follow the structure of P90X.

No matter what your end-goals, you almost always want to do a full round of P90X as designed, because it builds such a solid foundation. If you don't think you are ready for P90X, why not start with Power 90® or Slim in 6 to build your foundation for P90X. Either way, it's important to have a well-rounded fitness base regardless of what you're training for—whether it's a triathlon or a bodybuilding competition.
One of the most common reasons that people don't improve at a sport and get injured is by only training specifically for that sport and ignoring their base fitness. Get in the habit of thinking of P90X as high-level base (or foundation) training. The base you build with P90X improves your capacity for improvement for all other endeavors.
Periodization
Periodizational training came about when we figured out how long your body could continue to make improvements in one realm or another. It's all based around a progression curve where three things happen. First, you adapt to training (the adaptation phase). Next, you make rapid progress once your body masters the style of training (the growth or mastery phase). Finally, your body no longer makes improvements because it's too good at the chore you've given it, rendering your training too easy. Your progression curve then levels off, which is called a plateau. Whether a foundation program or a specialized program, all physical training follows the above progression curve example.
Progressive Overload
To keep your body from hitting a plateau, you must overload your system during each workout. Adding weight or intensity over time is referred to as progressive overload. In the simplest sense, each workout should be slightly harder than the last. When you can no longer achieve this, you've hit a plateau.
Recovery
Following the above progression will eventually lead to a plateau, no matter how precise your training is. When this happens, your fitness will only improve if you let your body recover or, more appropriately, do exercise that promotes recovery.
Putting It All together
Every sound fitness program will consider the above. Designing actual programs requires more knowledge and consideration, but these steps will be the template for everything you do.





