Sometimes running is hard. Sometimes it sucks.
But there is something about it that becomes addictive. I've said before, you mean not feel like running at times, but you never regret having run.
So what is they key? Consistency. Do it and the do it again. Create a schedule and stick to it. In the Skid Row Running Club, we run 5 miles every Monday and Thursday and then do a long run on the weekends.
Our Monday and Thursday runs start at 6am. That's early for a lot of people. Sometimes even I have a hard time getting up. We all do it because we want to develop a habit, we want to make it automatic and not think about it. When you think about having to go for a run, you start rationalizing all kinds of reasons why you shouldn't go for a run. Even when you run, you have a dialogue running in your head as to why you should or should not be running. You question your sanity at times and wonder why anyone would do this to themselves. Do let those doubts creep in! Just do it!
When run consistently, the more you enjoy it and the faster your become a better runner. Before you even realize it, it has become automatic, a habit. Than the consistency becomes natural. You know you will have become a lifelong runner when it no longer feels normal not to run.