I can't run.

Have you tried running outside/on a track as well as on a treadmill? I can run outside but once I try it on a treadmill, I can only make it a minute or two tops before I want to quit.

try warming up, not stretching... http://www.nerdfitness.com/blog/2012/01/09/warm-up/

^^ this

also as many have said, make sure you have the right shoes.

Wow! Thanks for all the tips everyone.

I think I should get fitted for a pair of proper running shoes. My current sneakers are less than a year old, and were about $100, but I've had several injuries to my right ankle as well, so maybe there is something wrong with my gait as well.

Running shoes can get 300-500 miles before they should be replaced depending on how heavy you are, how heavy you land, and your basic mechanics. It isn't a bad idea to pop into a running store every couple of months, try on the same model of shoes as the ones you currently have and feel the difference of new vs broken in until you get a feel for when your shoes need to be replaced. If the new shoe feels a TON better than the current shoe, replace, if it feels just a little bit better, keep the current.

The pain in your side sounds like side stitches. Stretching and warming up don't really do much for them, running slower does. As people have suggested C25K is a fantastic program to get you started with a slow build up which will help. At first your running may be real slow. My running spirit animal is a turtle, but I get it done. I get a lot of it done. I'm debating upgrading him to a turtle on roller skates, but that is off topic.

Injuries to your ankle. If you seriously want to start running you need to address these injuries, preferably with some professional help. See if you can get an evaluation with a physical therapist for guidance, and if need be a couple of visits to learn proper movements to stretch and strengthen the area. Problems with ankles often shoot up into your knee, hip and back because they throw everything out of alignment. Going back to the shoes thing above, you may find that after proper healing of your ankle you require different shoes as you mechanics will have changed.

Have you tried the Couch to 5K? That starts you off very slowly and builds it up to 3.1 miles by the end of it.

This.
I never thought I would be able to run. I tried and tried and always failed. But C25K made me a runner. It starts you running 1 minute intervals and leads you to running a 30 minute session.

I agree with the poster above who suggested having your feet fit at a running store. Good shoes make all the difference.

Also, the other issue may be speed and/or time interval of running. If you're running too fast, you could be exhausting your body. A good test is to speak a short sentence out loud while running. If you huff, puff and pant your way through the sentence, slow down; you're going too fast.
You may be increasing your run intervals too quickly and too much as well. The C25K program keeps the increases do-able and maintainable. Have a look at the schedule on-line and see how the run session times compare to what you're doing. Adjust, if necessary.

Keep running. You can do it.

Please join this group:
http://www.myfitnesspal.com/forums/show/47-couch-to-5k-running-program-c25k-

You'll find a tonne of information as well as a daily check-in thread where people at all stages of the programme are reporting their running experiences.

That's pretty much all I wanted to say. I exercise 30-45 minutes 3x week. I can do the elliptical or arc trainer at a medium-high intensity for this amount of time no problem, and often will follow up with a short walk (10-15 mins) to loosen up after.

But as soon as I try to run, even jog, I just. Can't. Do it. I will get this terrible pain (usually on my right side) within 1-2 minutes of jogging, even when I stretch beforehand. I don't know why this is so hard, when the other machines are so easy. Even when I "train" to try and build up my endurance, I can do 20 mins switching between walking and jogging, but instead of feeling good and refreshed after, my body really hurts, I have trouble walking, and it doesn't feel like I got a "good" workout.

I want to take up running. It's easy; you can do it anywhere. I'm very frustrated that the one type of exercise I really WANT to do is so hard for me.

Tips?

Don't run. It is not the be-all and end-all of exercise. Many people have lost a lot of weight and gotten fit by walking, biking, swimming, etc. If running isn't your thing, just find something that is.

Forgot to post this link:
http://www.goodformrunning.com

Do watch the Grant Robinson video also.

Oh...advil and ice are your best friends lol.

I haven't taken pain killers nor used ice once due to running. Just wanted to offer a second opinion.

I used to get side stitches ALL THE TIME when I first started running. When I get them, instead of stopping I try to run through them. If you can, kind of hold your hand on the area where it's hurting and breathe through it as you run. Also, do you try running pretty closely after you finish eating? That's another factor for me in it. I have to wait about an hour after I eat to run, otherwise I'm miserable.

Are you properly hydrated? Replenish those electrolytes!

Try C25K (free app) it starts out easy and you're able to slowly add some mileage onto your runs. Start slow and try to enjoy it

I am the same way. I can do almost anything, but run. I did the couch to 5k a few years ago AND worked with a trainer to do a 5K. I completed the 5K, but I am a very slow runner even with training for it hard for at least three months. I think some bodies just weren't meant to run and mine is one of them. Good luck!