You may want to take medication to lower your lipid profile. Exercise, proper diet, etc. will stop athrosclerosis (vessel occlusion, hardening of coronary arteries) and there is some evidence statins can reverse plague that tends to buildup and clog the arteries.
You may never require any intervention (stent or by-pass). I have a totally blocked LAD that has developed collateral vessels that provide a natural by-pass, and 70% circumflex artery that may or may not have decreased going on more than 4 years. Medication has been sufficient.