I want to do more cardio, but I'm not really sure how to go go about doing it. My stamina and endurance isn't the best (not the worst though!), and often when I get off the elliptical after being on it for a half hour I feel so dead that I can't do it again.
Would it be better to do smaller incriments of time over the course of the day (10 or 15 minutes of hard work on the elliptical, multiple times) so that I can possibly do more that way without wearing myself out too fast, or just doing the bigger chunks of time (like a half hour at a time), and try to do that more than once? I've heard that it's important to keep your heart rate up for longer periods. Does this difference matter that much?
I hope this isn't too confusing.