The last rep, when your arms are shaking, counts more than the ten that felt easy.

Adaptation happens at the edge of what you can currently do, not in the comfortable middle. The reps that feel manageable are maintaining, and the one that is barely possible is the one asking your body for something new. That is why the end of a set matters disproportionately, and why stopping when it gets hard leaves the work undone.

Stay honest about where your actual limit is rather than where the discomfort starts. Give the last repetition your full attention and good form. One more careful rep is worth more than five extra easy ones.