I've been through the newb->novice->competent->proficient process a few times, and the thing that's kept me going was the goal of reaching proficiency. During the process, I'd always be my own harshest critic, because I'd be acutely aware of all of my weaknesses.
Any praise I'd receive would be rejected, because in my own head the person would be ignoring all of the obvious issues with what I was doing.
I understand that not everyone responds in this way, but personally I think it's easier to succeed when the motivation comes from within, rather than relying on an encouraging environment which ultimately you can't really control.