You're not a failure, you're still trying! You can't fail if you never give up. Yes, sometimes it is a very long road -- but so be it -- it is still worth traveling!
I agree with the other posters: focus on each day.
And prepare yourself ahead of time for when you make a mistake. We all make mistakes. So when you make your first mistake (no matter when it happens) don't chuck away your commitment and planning and your desire and your hard work. Acknowledge the mistake, forgive yourself, and MOVE ON, get right back on the horse. This sounds so simple but it is one of the hardest things to do, and why it is so easy to fall off plan for long periods of time.
Good luck to you!