Having some doubts...

I'm usually a very optimistic person. I am also usually a very realistic person, which sometimes causes optimisim to fly right out of the window.
I am seriously wondering and questioning...can I really do this? Can I run a 5K at the end of the month?
I'm having some doubts. In less than a month, I'm just not sure I will be able to run approximately 3 miles without stopping. Without stopping. That was my goal. Not running a part and walking a part. My goal was to run it. The whole thing. It's on my "things I want to do this year" list. I so want to cross that one off. For once, I want to meet a goal. I want to do it for my biggest critic - the person who is always telling me I can't do it. That person is myself.
I know partly why I feel this way...I didn't push myself last week. I ran one day. One day. I just couldn't get motivated. I still worked out...and I still lost weight...but I slacked off on running. I made myself go today and I can honestly say, I pushed myself. I usually run hard during the beginning and flake out at the end of my 5K run at the gym. But, today, I ran .05 miles at a time and walked .05 miles - for a total of 3.1 miles (a 5K). In other words, I was consistent through the whole workout instead of just giving my all at the beginning and ending up walking the rest. So, overall, today - I ran as much as I walked. I'm really going to try to get up to running .07 miles then walking .03 and repeating until I get to 3 miles by this Saturday. I have seriously got to push myself through this. I knew it would be hard.
Sometimes before I go to the gym, I psych myself out. When I start to think how hard it's going to be - I'm already unmotivated before I even begin. But when I just think of it as .01 mile at a time, it helps. Before I know it - I'm at a half of a mile and I think I can go one more tenths of a mile. And I do. It feels so good when I push myself and I accomplish more than I set out to do. I have to remember that. I have to.
Here's to setting high...and attainable goals.