Training should not mean pushing through pain and hoping for the best. A generic workout can sometimes cause flare-ups because it does not account for how your knee feels on a particular day.
Your trainer watches how you move, asks how your knee is responding, and adapts the session in real time. That may mean changing an exercise, reducing the range of motion, adjusting the load, or focusing on mobility and stability instead.
If you experience severe pain, swelling, locking, or a sudden change in your symptoms, stop exercising and consult a healthcare professional.