I first trained to run long distances using a run-walk method for equal distances, which I then shortened – it took some convincing from an experienced runner that I wasn't "cheating", but when I realized that I was able to run at enough overload to train no matter what, it then clicked: it's about staying in motion; it's running, not sprinting, which are two different things indeed.

I now cycle for the same reasons as you do, although it's not as consistently intense as I would like.