Record the exercise, load, reps for each set, and how much effort the sets took. Keep a note of setup changes that affect the movement.
Compare the same exercise under similar conditions. An extra controlled rep at the same load and similar effort can be useful progress. When your current target becomes consistently manageable, your program can guide a small increase in difficulty.
Look across several sessions. One difficult day is a reason to look at the context, rather than rewrite the whole program.
Next session: open your previous workout before your first working set.
Further reading: ACSM’s progression models for healthy adults .