Nothing works forever: adaptation and progression
As much as we all look for the perfect program, exercise or nutrition plan, the fact is, most will work for a while given that they are appropriate for you at that time.
How many times have you started a “diet” or a new fitness class which saw you achieve good results early on only for progress to slow and then stall, or added a new exercise to training which induces crippling soreness in the next day or 2 only to find that a couple of weeks later you’re now able to walk down the stairs freely the next day and sitting on the toilet isn’t an intense mental and physical challenge. This is a result of adaptation, you’ve stressed your muscles and at first they struggled to cope, hence the soreness, but they have learnt to deal with that stress and are prepared for what you’re asking them to do. This is progress.
But here’s the catch ...
Unless you continue to apply further stress to those muscles, adaptation can’t occur and progress stalls and you can even regress. Further stress can be applied in numerous ways such as adjusting weight, volume or frequency, decreasing rest or varying an exercise. This isn’t too say you should change exercises every session but some sort of progressive plan is what’s needed to achieve further success in your chosen goal.
This also applies to nutrition, if tomorrow you were to increase or decrease your calorie intake by 1000 (I’m not recommending you do this), the body will react with drastic changes, but once it has adapted to these drastic measures, if no further disruptions take place, no further change will occur.
So don’t get stuck in a rut, keep forcing progress, you will be surprised of what you’re capable of.