Gratitude defines your attitude towards life. We keep talking about positive thinking but until and unless we are truly grateful for our life and of who we are, no positive thinking will ever do the job.
So the next question naturally would be how to do stay in a state of gratitude? It is simple. Compare yourself to what you were 12 months back, or 2 years back. Even if you are doing slightly better now that is an achievement in itself.
So the next time your inner critic is not being kind, when self doubt is screaming at you, remind yourself how far you have come. And that you are meant to go further now. It is not the end until you start believing it is.