I personally find it harder outside as well. That said, I live in a city that is notoriously 'hill-y'.
Depends, if you're running on the street it's a bit like running cross country because of the change of surfaces
When I started running I was 360 pounds and couldn't run across the yard. I charted out a mile course. Each day I ran as far as I could, then walked the rest. When I could run the whole thing, I ran it, then walked it. Then one day I discovered I could run it twice. After that 5 miles was easy. The whole process took about 2 months. Btw I rested 2 days a week, sometimes 3 if I had a particularly hard day at work.(I worked construction). edit: Saw your question about treadmill vs outdoors. Treadmill is good for cardio, anything that makes you breathe hard for longer than 20 minutes is good for cardio. It will not build your leg muscles for running like real running will though, as it does a lot of the pushing off for you. I would recommend you sign up for a local 5k run. Just google 5k run and your city/state. That will give you a goal to shoot for, in fact it's what i'm doing, and why i'm in the training forum. I just haven't made my thread yet.
I now run treadmill and outside. Outside is deffinatly harder on the joints and is deffinatly not good for you in that sense. However its a far greater challenge ( here he goes again) MENTALLY lol. When its raining or hailing, snowing ect. Or its just freezing cold it feels alot more challenging and alot more rewarding than a treadmill. That said personally i have trouble if i run on the road all the time with my joints so i find the treadmill a good "rest" in between road runs.
There are also great feelings that come with running outside, once you are at the point where you are in shape and just enjoying the run. Nothing like the feeling of running on a narrow trail with high grass just flowing past you. Or running somewhere with a purpose and destination, feeling like you are your own vehicle. I used to run to my friend's houses to visit them, even though I had 2 cars and they lived 3-5 miles away.
I know its an amazing feeling. I went on holiday to scotland for 2 weeks about 3 weeks ago. Now there was some good running!!! People thought i was mad running on my holiday, dont think they understand the feeling you get when you run up and down hills for 6 miles to reach a castle thats on a cliff on the side of a loch lol!
No matter how down i get or depressed when ever i go out for a run i always feel alot better is that the endorphines? My personal best on a half marathon is 1 hour 28 minutes and 10 seconds doing my first marathon in september, Good to see everyone running no matter what your goal is if its running to get back in to shape running a 5k or a marathon heres an old runners saying "Its the courage to start which is impressive not the courage to finish"
i havent ran in i think 4 months after smokin and drinkin consistently i quit smokin for 2 days then today i ran 5 miles with no problem other than slight hip pain at a nice pace to so it all depends on the man i think but i used to run a lot so that probably has somethin to do with it.the key is breathin always through ur nose never out the mouth.