I increased my cardio. Specifically doing short bicycle sprints on my real bike. I have a special seat that puts zero pressure on the crotch – its a split two part seat.

So I am getting boners much much more now & my cardio is way better. I recommend some high intensity cardio – these cycle rides only last 20 minutes max.

It must be a combination of the general heart action & the thigh pump in the crotch. It is definitely training in the lactic acid overload region & high heart rate.