Heya Jonestown (-:

I'd recommend instead to do full-body NEW exercises, with the intent to undo blocks and get energies flowing better. In a body where energy flows well, particularly chi channels, there is more vital energy to go around. And since cardiovascular endurance is not just based on the heart's strength, but also on the health and number of blood vessels and the ability of your body to metabolize energy in the blood and muscles, a more wholistic approach makes sense anyhow, and dodges any issues that might come up with overstimulating the heart itself.

Be well.