hairy_pete wrote:Stuart, that all sounds like you need to build up your endurance foundation first.
If you're feeling completely fucked after a few minutes, you're going too fast. Set a slower pace, one that keeps your heart rate at midrange levels. This enables you to keep going for long enough to make it an actual endurance exercise. Once you feel an improvement, keep the same pace (same heart rate) but make it even longer. When you're comfortable with that 2nd stage, you can also begin to add shorter, faster sessions.
QFT.
I used to run loads when I was younger. Motivation was the key - being the oldest of 13 kids I just needed time by myself, so got it by going out for a jog. I always took a straight route (you have to get back after) and tried to go past the next corner each day or thereabouts. After I year I was running 28 miles a day. Carried nothing but money for bus fare in my sock, which was just in case I couldn't make the return journey, and I happily stopped whenever I saw something interesting.
I am starting to do it again now, and even though i'm unfit as fuck I laugh when I see some people jogging at full pelt then collapsing a mile after, or those that spend more energy bouncing up and down than going forward.
The point is, do exercise you enjoy and don't feel compelled to do it faster/harder than is comfortable, because comfortable will get easier every time you exercise. The 'next corner' thing kept me going, even though I didn't manage it every day, and if you use it as a tool rather than a challenge you get fitter and won't give it up because you feel crap.