I wrote a blog about Why I Run back in June www.sparkpeople.com/mypage_public_journal_
My good running days out number the bad ones now. In fact, I went for a run yesterday and only did 3.5 miles (generally go 4-5) and walked about a mile of it - I just felt off. I'm sure my next run will be fine, though.
Good luck on your running - but I also tell people if they don't like running then don't do it - not everyone has to like it...there's lots of other activities out there.