Finally, as you keep training regularly, you will adapt and get stronger, so your workouts have to get progressively more difficult. That ample amount of resistance when you first started will soon become too easy and will no longer be enough to induce any improvements in strength.

If you want to keep getting stronger, then your workouts will never get easier.

There are hundreds of ways to make different programs with as many different philosophies of training but they all have to obey the above three rules if you want to build strength.