That has been a good increase over three years and a nice thing to see. You don't say what your cause of low EF was. Taking it that the EF was caused by blood pressure problems or something usually reversible, then the current regime of medication is obviously working well. I would also ask your cardiologist what level of exercise you can do, what he recommends as your maxiumum heart rate for exercise. What you don't want to do is lots of vigorous exercise and cause your muscle to weaken again before it has further recovered. SOME level of exercise is always good, but your cardiologist needs to tell you the limitations. It should be a normal consultation with your cardiologist, called heart management.