Lutheran,
There are two approaches: one is to keep your LDL choilesterol down as low as you can...below 100 or better; the other is to do regular high intensity aerobic excercise to cardiac heart rates.
The first will prevent laying down more plaque and even reduce it slowly but this might entail statin drugs. What are your cholesterol numbers.
The SECOND approach will build a system of collateral vessels that can keeep you alive in the event of a blockage that goes to 100%. That's a sustained heart-rate of about 151 for your age.
Do both!
(It's good that you are taking interest at a level of 30% rather than at a level of 80% blockage.

)