Good Enough vs Not Good Enough

I've read alot about people accepting good enough and moving on without ever learning their full potential.  I think the opposite can be damaging as well.  I often think "not good enough"...it makes me so frustrated when I'm not good at something and I don't get there as quickly as I think I should and 90% of the time, I just give up.  I think a good balance is essential.  I think you need to develop recognition that you are good enough for now, can be better and will strive to be better.  I think either extreme is unhealthy.  I am extremely hard on myself, there's no one in this world that will criticize me more than I will.  I need to learn to be comfortable with my current capabilities and be alright with working on my weaknesses one step at a time without damaging my self worth and running away from things all the time.  Right now, I'm more out of my comfort zone than I ever have been and I'm teetering between giving up and moving forward and I'm really trying not to quit.