answer:Good cardio exercise is good cardio, period. What label it comes under is more about the latest push to make money marketing something that’s been around at least since mankind built the pyramids as something that’s all new. And the fact that after trying one for a period of time, you’re ready to chuck it and buy a different one proves that marketers are winning—or should we say insanity triumphs? Not to be too harsh on you. Running intervals at 15 below zero would be truly insane, and you’ve all been smart enough not to go there. It might make sense to get a treadmill or join a gym for access to such. That would resurrect the running. A little change-up in exercise routine from time to time is a good thing. First, it helps ward off boredom with it. Second, if you notice the current routine leaves some muscle group you want to build up untargeted, you can search Google for things to add to tone the areas that still need it. But don’t buy one after another video/book/tape touting the all new incredible plan that beat’s all others. The only part of new exercise routines that in truth keeps beating all previous ones is the wildness of the marketing claims (the BS) used to marketi them. That, in truth, does keep getting piled higher and deeper.