I'm going by the assumption that, aside from genetic reasons, a circulatory system can in principle be kept in good shape through diet and exercise.
I think the first step is to focus on things that we don't have a solution for. Having good diet and exercise is a fairly comprehensive solution, no matter how hard it might be to maintain a lifelong strict regimen (as long as you're able to have such a regimen, your chances of the circulatory system going bad are slim to none).
In the case of organ failure, we don't even have anything other than reliance on organ availability from others.
I think the first step is to focus on things that we don't have a solution for. Having good diet and exercise is a fairly comprehensive solution, no matter how hard it might be to maintain a lifelong strict regimen (as long as you're able to have such a regimen, your chances of the circulatory system going bad are slim to none).
In the case of organ failure, we don't even have anything other than reliance on organ availability from others.