Train until your confidence is surprised by how conservative it once was.

Get far enough into training something and you will look back at what you once considered a reasonable expectation and find it strangely small. Not because you were foolish, but because the estimate was made from a place with much less information. That backward surprise is one of the more reliable signs that real development has taken place.

Write down what you currently think you could achieve in this area, and put the note somewhere you will find it in two years. Then get to work. The comparison later is usually more instructive than any amount of encouragement now.